Class 6 Science

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Review Questions Environment Review Questions MCQs

Question 1. SI unit of pressure is

1. Newton
2. Pascal
3. Bar
4. Newton/Metre

Answer: 2. Pascal

Question 2. Pressure = Force/Area. With reference to this formula state which principle is applied in nail The to increase its pressure

1. Area is increased
2. Both area and force are increased
3. Area is decreased
4. Force is reduced

Answer: 3. Area is decreased

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Question 3. Liquid flows from

1. Lower pressure to higher pressure
2. Higher pressure to lower pressure
3. All of the above
4. None of the above

Answer: 2. Higher pressure to lower pressure

Question 4. As the depth of water increases

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1. Only downward pressure would increase
2. Only upward pressure would increase
3. Only lateral pressure would increase
4. Pressure in all directions would increase

Answer: 4. Pressure in all directions would increase

Question 5. Faster the rate of airflow, the ____________ the pressure.

1. Higher
2. Lower
3. Same
4. None of the above

Answer: 2. Lower

Question 6.If more force is applied on a certain surface area, pressure

1. Increases
2. Decreases
3. Remains the same
4. None of the above

Answer: 1. Increases

Question 7. The lower portion of a dam’s wall is

1. Thinner
2. Same throughout
3. Broader
4. None of the above

Answer: 3. Broader

Question 8. The three surfaces of brick have an area of 50 sq. cm, 30 sq. cm, and 20 sq. cm respectively. The brick is released on mud in three ways so that its different surfaces come in contact with mud. The penetration of the brick inside the mud shall be maximum when it falls with its hot

1. 50 sq. cm surface facing the mud
2. 30 sq. cm surface facing the mud
3. 20 sq. cm surface facing the mud
4. Same in all of above

Answer: 3. 20 sq. cm surface facing the mud

Question 9. Fluid means

1. Gas only
2. Liquid only
3. None of them
4. Both of them

Answer: 4. Both of them

Question 10. The following is an airplane wing. Which of the following statements is true?

 

1. V is greater than V, but P is smaller than P2
2. V is smaller than V, but P is greater than P2
3. V1 is greater than V2 and P, is greater than P2
4. V is smaller than V, and P is smaller than P2

Answer: 1. V is greater than V, but P is smaller than P2

Question 11. The pressure exerted by a fluid depends on

1. Quantity of the liquid
2. Depth of the liquid
3. The shape of the vessel
4. The volume of the liquid

Answer: 2. Depth of the liquid

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Question 12. Pressure Force/Area In the light of this formula state which principle is applicable in the design of a camel’s feet.

1. Area is increased
2. Both area and force are increased
3. Area is decreased
4. Force is reduced

Answer: 1. Area is increased

Question 13. Application of Bernoulli’s theorem can be seen

1. In making an airplane wing
2. When tornados cause upliftment of roofs
3. In a spray atomizer in a perfume bottle
4. All of these

Answer: 4. All of these

Question 14. According to Bernoulli’s principle, a moving fluid has

1. No pressure
2. More pressure where speed is more
3. Less pressure where speed is more
4. Constant pressure irrespective of speed

Answer: 3. Less pressure where speed is more

Question 15. 1 kilo Pascal =

1. 1000 Pascal
2. 1000 Newton per m2
3. 0.1 Newton per cm2
4. All of these

Answer: 4. All of these

Question 16. The ground floor water tap of a building shows a pressure of 100 kPa. What will be the pressure in a tap on the tenth floor of the building?

1. 100 kPa
2. More than 100 kPa
3. Less than 100 kPa
4. None of these

Answer: 3. Less than 100 kPa

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Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Fill In The Blanks

Question 1. 1-kilo Pascal= __________ Pascal.
Answer: 1000

Question 2. The pressure of water __________ with the increase in depth of a well.
Answer: Increases

Question 3. Force = Pressure x __________
Answer: Area

Question 4. All __________ and __________ are regarded as fluids.
Answer: Liquids, Gases

Question 5 A moving fluid has less pressure at the place where its speed is __________
Answer: More

Question 6. The lower portion of a dam is made __________ than its upper portion.
Answer: Broader

Question 7. Fluid flows from a place with a __________ pressure to a place with a __________ pressure.
Answer: Higher, Lower

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Question 8. The top of the wings of an airplane is somewhat __________ while the bottom is __________.
Answer: Curved, flat

Question 9. A force of __________ produces a pressure of 20 kPa when it acts on a surface having an area of 10 sq.m.
Answer: 200 kN

Question 10. A sharp knife generates __________ pressure at its cutting surface than a blunt knife.
Answer: More

Question 11. \(\frac{1 N}{1 sp.m}\) = ?
Answer: 1 Pa

Question 12. The pressure which a fluid exerts on the sides of the containing vessel below the free surface is called __________ __________.
Answer: Lateral Pressure

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Identify As True Or False

Question 1. Pressure in liquid decreases with depth.
Answer: False

Question 2. Thrust Pressure x Area
Answer: True

Question 3. Gases diffuse from a place of higher pressure to a place of lower pressure.
Answer: True

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Question 4. A rubber sucker works on the principle of atmospheric pressure.
Answer: True

Question 5. Fluids do not exert pressure.
Answer: False

Question 6. Pressure is different at all points in a horizontal plane at a given depth within a liquid.
Answer: False

Question 7. Storms flow away thatched roofs of huts when inside pressure exceeds that in the outside.
Answer: True

Question 8. A pointed nail goes easily inside a wooden plank after hammering.
Answer: True

Question 9. Bernoullis’ principle has more application with regard to airflow than liquid flow.
Answer: False

Question 10. Increasing the applied force on the same area decreases the pressure.
Answer: False

Question 11. A blunt knife is more useful for cutting than a sharp knife.
Answer: False

Question 12. 1 kilo Pascal = 1000 Newton per square meter.
Answer: True

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Match The Columns

Answer: A-4,B-2,C-3,D-5

 

Answer: A-2,B-3,C-4,D-1

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Answer In Words Or A Sentence

Question 1. If the area is doubled keeping the applied force the same, what would be the change in pressure?
Answer: Pressure becomes half the previous.

Question 2. How does pressure change with the speed of moving liquid?
Answer: The pressure of liquid decreases with an increase in the speed of moving liquid.

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Question 3. In which direction does air flow?
Answer: From a place of higher pressure to that of lower pressure.

Question 4. What are the units to express atmospheric pressure?
Answer: Atmosphere (atm), Pound per square inch (psi), and Bar (bar).

Question 5. In which direction does a liquid exert pressure at any point below its free surface?
Answer: In all directions.

Question 6. What is the pressure acting at the free surface of a liquid?
Answer: Atmospheric pressure.

Question 7. What is the principle applicable behind the flight of a bird?
Answer: Bernoulli’s principle.

Question 8. If 100 N force is applied on a surface of 25 sq. m area, what is the applicable pressure?
Presure=\(\frac{Force}{Area}\)=\(\frac{100 N}{25 sq.m}\)=4 pa

Question 9. Which one is difficult to penetrate inside a block-a sharp-ended nail or a blunt-ended nail?
Answer: Blunt-ended nail.

Question 10. How does air pressure vary at a hill station compared to that of a plane landing at sea level?
Answer: Air pressure at the hill station is lesser than that at sea level.

Question 11. Flags flutter while there is a breeze-which principle does this phenomenon follow?
Answer: Bernoulli’s Theorem on fluid flow and pressure.

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Question 12. On what factors does a pressure of a liquid depend?
Answer: At a certain place the pressure at a point inside a liquid increases with the depth from the free surface of the liquid.

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Short Answer Type Questions

Question 1. A boy weighing 30 N falls on the sand. The area of his feet is 0.001 sq. m. What is the pressure exerted on sand?
Answer: 

Pressure=\(\frac{Force}{Area}\)=\(\frac{100 N}{0.001 sq.m}\)

Question 2. Why is it difficult to hold a school bag having a strap made of a thin and strong string? Pressure = Force/Area.
Answer: Thus as the area decreases, pressure increases. Since the contact surface area of a thin string strap is very small, it exerts large pressure on the shoulder making it difficult to carry.

Question 3. What makes house lizards stick to the wall when they crawl?
Answer: Lizards have hollow cavities inside the soles of their feet which help suck out the small pockets of air from the spots where they stand.

The higher atmospheric pressure helps them to stick to the surface of walls and ceilings.

4. Why are dams broader at the base than at the top?
Answer: Pressure at a point inside the liquid increases with the depth from the free surface of the liquid.

This lateral pressure multiplied by the area of the dam gives the force exerted by the water on the walls of the dam. The force at the base is higher than at the top.

Hence dams are constructed with a broader base to prevent the development of cracks.

Question 5. If force remains the same, how can pressure be increased?
Answer: If the area decreases, pressure increases when the force remains the same.

Question 6. Why does a capped plastic bottle filled with steaming hot water get deformed when it is allowed to cool?
Answer: As the steaming water in the bottle begins to cool, the pressure inside the bottle reduces.

However, the pressure outside the bottle remains the same. This excess outside pressure deforms the bottle.

Question 7. How is water supplied in cities?
Answer: The dependence of pressure in liquids on depth is made used in supplying water to different parts of a city. Water is stored in big tanks which are placed at great heights.

From these tanks, water is sent to different parts of the city through pipes.

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As the water tanks are placed at great heights, the pressure in the water, being very large, forces the water to rise in multi-storied buildings.

Question8. The figure shows a container filled with water. At which point is the pressure highest?
Answer: Point C is at maximum depth from the free surface of the water. Hence lateral pressure of water is highest at C

Question 9. Three vessels are shown in the following figure. The volume of water is the same in all of them. Arrange the
Answer: vessels in the order of increasing pressure at the base of each vessel.

The height of the water column is maximum in vessel B and minimum in vessel C. Accordingly pressure at the base shall be maximum in vessel B and minimum in vessel C.

Thus when arranged in the order of increasing pressure at the base, the vessels shall be Vessel C< Vessel A < Vessel B.

Question10. A liquid seeks its own level-explain it.
Answer: A liquid, irrespective of the shape of the container of a communicating vessel in which it is poured, attains its own level because the pressure applied at the bottom of each container remains the same.

The surface of the liquid in every container is found to be horizontal at rest. This fact is often known as liquid finding its own level.

Question 11. Why do flags flutter when air is blowing?
Answer: When air is blowing, the air layers are moving with unequal velocity on the two faces of the flag.

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According to Bernoulli’s theorem, the air layers flowing at a slower speed have higher pressure while those flowing at a faster speed have lower pressure.

Thus a difference of pressure is created on both sides of the flag which results in fluttering of the flag.

Question 12. On what factors does the thrust exerted by a liquid on the base of a vessel depend?
Answer: Thrust or force exerted by a liquid on the base of a vessel depends upon

1. the height of the liquid column in the vessel. More the height, the greater the thrust, and vice versa.
2.  the area of the base of the vessel. For a certain height of the liquid column, more thrust will be there on the base of the vessel having a bigger base area.

Chapter 7 Statics And Dynamics Of Fluid Liquid And Gas Long Answer Type Questions

Question 1. What is pressure? What is its unit in the Sl system? When somebody walks on pebbles, he feels greater pain than walking on a flat floor explain.
Answer:

Pressure:

Force per unit area of surface is your whole foot, much more of the pressure is called pressure.
Pressure Force/Area.

The SI unit of force and area are Newton and square metres respectively. Hence SI unit of pressure shall be Newton per square meter.

It is also called Pascal or Pa. Multiple of Pascal is kilo Pascal.

1 kilo Pascal = 1000 Pascal = 1000 Newton per square metre.

Now we shall go back to the previous example and try to analyze what causes more pain to walk on pebbles than on sand and how is it related to pressure.

This is because of the applied to the small area that is actually touching the pebble. So, more pressure applied on a given area of your foot causes more pain.

Let us take another example. Try to hit two nails-one having a blunt end and another having a sharp end into a wooden block by a hammer.

You would observe that the sharp-ended nail penetrates the block more easily than the blunt-ended one.

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Since the area of the sharp-ended nail is less compared to the blunt-ended one, it generates more pressure for penetration than the other nail and thus penetrates relatively easily.

Question 2. What is Bernoulli’s principle? Why are people warned to move away from the edge of a platform when a fast-moving train comes?
Answer: You know the behavior of a river in a wide, unconstricted region, it flows slowly, but if its flow is narrowed by canyon walls (for instance), then it speeds up dramatically.

Now imagine that fluid moves from a wider pipe to a narrower one. Certainly, the volume of that fluid that moves a given distance in a given time period does not change.

But since the width of the narrower pipe is smaller, the fluid must move faster in order to achieve that result.

Bernoulli’s principle states that a slow-moving fluid exerts more pressure than a fast-moving fluid.

Since “fluid” in this context applies equally to liquids and gases, the principle has as many applications with regard to airflow as to the flow of liquids.

We shall illustrate the above principle with another example. Suppose there is a room full of children.

If each child is asked to run at top speed, children will start bouncing off each other and the walls resulting in a number of collisions.

Now if those same children are taken out of the room and again asked to run down a wide hall at top speed, they would be all said? running together.

This time all collisions between children are much more gentle than before since they are all running in the same direction.

Hence Bernoulli’s conclusion The slower the rate of flow of a fluid, the higher the pressure, and the faster the rate of flow, the lower the pressure.

Take a piece of folded paper and hold them. in front of your mouth. Blow air in between the. papers, as shown in The papers, come.

closer instead of going apart. When air moves faster in between the papers (due to blowing), the pressure decreases in that region. The force.

exerted by air outside the papers act perpendicular to the outer surface of the two sheets and push them together.

One of the most common everyday applications of Bernoulli’s principle is in air flight. The main way that Bernoulli’s principle works in air flight has to do with the architecture of the wings of the plane.

In an airplane wing, the top of the wing is somewhat curved, while the bottom of the wing is totally flat. While in the sky, air travels across both the top and the bottom of the wing concurrently.

Because the top part and the bottom part of the wing are designed differently, this allows for the air on the bottom to move slower, which creates more pressure on the bottom, and allows for the air on the top to move faster, which creates less pressure.

This is what creates a lift, which allows planes to fly.

A person standing near the railway track is pulled towards the train when a fast-moving train passes close to him. The fast-moving train decreases the pressure between the person and the train.

Question 3. Define the lateral pressure of the liquid. Explain with a diagram what happens when three holes are made at varying heights in a bottle filled with water.
Answer: Any substance which has no fixed shape and can flow is called fluid. All liquids and gases are regarded as fluids.

Do fluids exert pressure? Does it also depend on the area on which the force acts? We have seen that a solid exerts pressure on another surface on account of its weight.

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Similarly, a fluid has weight and hence, it exerts pressure on the walls of the container in which it is kept or enclosed.

It may be demonstrated as shown in means that they need to reduce their Dit pressure on the ground. Large feet mean a large area of contact and thus less pressure.

A piece of thin and good quality rubber sheet may be tied tightly over at one end of a long glass tube.

While holding the glass tube in the middle and in an upright condition, some water may be poured into the tube.

It would be seen that the rubber sheet would bulge out indicating that Statics and Dynamics of Fluid (Liquid and Gas) water exerts pressure.

While walking down the streets you must have come across situations. where fountains of water are seen to come out of the leaking joints or holes in municipal water pipes supplying water to the city.

This happens due to the pressure exerted by the water on the walls of the pipes. When you inflate a balloon, you have to tightly close the mouth immediately or else the balloon deflates rapidly leaking out all the air.

There are certain laws of liquid pressure. These are as follows:

1. Pressure at a point inside the liquid increases with the depth from the free surface of the liquid.
2. Pressure is the same at all points in a horizontal plane at a given depth within the liquid.
3. A liquid flows from a place of higher pressure to a place of lower pressure.
4. A liquid seeks its own level.

Now we would explain one after another with simple demonstrations. Let us take the first law which states that pressure increases with the depth of a liquid from the free surface.

Let us prove it with the following example. A plastic bottle filled with water may be taken similar to the one shown earlier.

Three holes shall be made in the bottle one above another from top to bottom in a line.

It would be found that the flow of water from the bottommost hole travels furthest because the pressure exerted at this point is the highest since this hole is situated at maximum depth from the free surface of the water.

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Question 4. Why do we not feel tremendous atmospheric pressure? Why does a rubber sucker require a large force to pull it off a surface?
Answer: The envelope of air surrounding us is called the atmosphere. It extends up to many kilometers above the surface of the earth. The pressure exerted by this column of air is known as atmospheric pressure.

If we imagine a unit area on our head as shown in and a very long cylinder standing on it filled with air, then the weight of air belonging to this cylinder shall be the atmospheric pressure.

The reason we are not crushed under this weight of the air column is that the pressure inside our bodies is also equal to the atmospheric pressure and it cancels the pressure from outside.

Why do some passengers suffer from nose bleeding in pressurized aircraft cabins? As the altitude increases.

the air pressure decreases around passengers and therefore this can cause nose bleeding in some cases since the pressure inside the human body becomes more than that at the outside at higher altitudes.

The cabin is pressurized but not as much as it is at sea level. Therefore, it’s common among many people to have nose bleeding and is not usually a serious problem.

There are certain laws of liquid pressure. These are as follows:

1. Pressure at a point inside the liquid increases with the depth from the free surface of the liquid.
2. Pressure is the same at all points in a horizontal plane at a given depth within the liquid.
3. A liquid flows from a place of higher pressure to a place of lower pressure.
4. A liquid seeks its own level.

Now we would explain one after another with simple demonstrations. Let us take the first law which states that pressure increases with the depth of a liquid from the free surface.

Let us prove it with the following example. A plastic bottle filled with water may be taken similar to the one shown earlier.

Three holes shall be made in the bottle one above another from top to bottom in a line.

It would be found that the flow of water from the bottommost hole travels furthest because the pressure exerted at this point is the highest since this hole is situated at maximum depth from the free surface of the water.

Question 5. Draw a diagram to show how thatched roofs are blown away by high winds or tornadoes.
Answer:

Chapter 6 Primary Concept Of Force And Energy Review Questions Environment Review Questions MCQs

Question 1. SI unit of force is

1. Dyne
2. Kg
3. Newton
4. None of these

Answer: 3. Newton

Question 2. Magnet attracts

1. Iron nails
2. Eraser
3. A plastic scale
4. Wooden pencil

Answer: 1. Iron nails

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Question 3. Force can change a body.

1. Mass
2. Weight
3. Density
4. Shape

Answer: 4. Shape

Question 4. SI unit of weight is

1. Gram
2. Dyne
3. Density
4. Shape

Answer: 4. Shape

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Question 5. An object that has kinetic energy must be

1. Lifted above the earth’s surface
2. In motion
3. At rest
4. None of the above

Answer: 2. In Motion

Question 6. As height increases, so does

1. Thermal energy
2. Chemical energy
3. Atomic energy
4. Potential energy

Answer: 4. Potential energy

Question 7. _________ is a non-magnetic substance.

1. Wood
2. Cobalt
3. kg
4. Newton

Answer: 1. Wood

Question 8. Which is the major advantage of using sources such as sunlight, wind, and running water instead of fossil fuels, such as coal and natural gas?

1. Sunlight, wind, and running water are much more efficient than fossil fuels
2. Sunlight, wind, and running water are renewable and available indefinitely
3. Sunlight, wind, and running water are much less expensive to use than fossil fuels
4. Sunlight, wind, and running water can be used at any geographical location

Answer: 2. Sunlight, wind, and running water are renewable and available indefinitely

Question 9. When a boat sail forward, it uses

1. The frictional force of air
2. The potential energy of air
3. The kinetic energy of air
4. The chemical energy of air

Answer: 4. Chemical energy of air

Question 10. Man is ___________ but cow is

1. Herbivore, omnivore
2. Omnivore, herbivore
3. Carnivore, herbivore
4. Omnivore, carnivore

Answer: 2. Omnivore, herbivore

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Question 11. If a football is rolled on the field, it stops after traveling through a certain distance. The responsible factor for this incident is

1. Mass of the ball
2. The shape of the ball
3. Force of friction
4. Force of gravity

Answer: 3. Force of friction

Question 12. Which of the following food chain is not correct?

1. Grass Grasshopper→→Toad→Snake Mongoose
2. Leaf of plant→→→Locust→→Myna
3. Leaf of plant->Rabbit->Hawk T2300
4. Grass Dear→Giraffe

Answer: 4. Grass Dear→Giraffe

Question 13. The food you eat and fossil fuels are both examples of this form of energy.

1. Atomic energy
2. Thermal energy
3. Chemical energy
4. Mechanical energy

Answer: 3. Chemical energy

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Question 14. What device among the following converts chemical energy to mechanical energy?

1. Human
2. Car
3. Jetski
4. All of these

Answer: 4. All of these

Question 15. Which of the following is the best example of increasing an object’s potential energy?

1. Rolling a bowling ball
2. Turning on a light bulb
3. Dropping a light bulb
4. Stretching a rubber band

Answer: 4. Stretching a rubber band

Question 16. Which one is a primary consumer?

1. Grass
2. Goat
3. Tiger
4. Vulture

Answer: 2. Goat

Question 17. Energy flow in an ecosystem is

1. Unidirectional
2. Bidirectional
3. Multidirectional
4. Reversible

Answer: 1. Unidirectional

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Question 18. On which surface will a toy sled travel the furthest?

1. Rock
2. Carpet
3. Polished wood
4. Ice

Answer: 4. Ice

Question 19. Energy transfer from one trophic level to another in a food chain is

1. 1%
2. 10%
3. 2%
4. 20%

Answer: 2. 10%

Question 20. Potential energy is

1. Stopped energy
2. Thermal energy
3. Stored energy
4. Moving energy

Answer: 3. Stored energy

Question 21. All forms of energy which are available on earth have their origin from

1. The chlorophyll
2. The sun
3. The nuclear fission
4. The tides

Answer: 2. The sun

Question 22. The beating of a drum with sticks produces ___________ from ___________

1. Sound energy, mechanical energy
2. Mechanical energy, sound energy
3. Sound energy, electrical energy
4. Sound energy, heat energy

Answer: 1. Sound energy, mechanical energy

Question 23. Magnetic attraction is a type of

1. Frictional force
2. Gravitational force
3. Contact force
4. Non-contact force

Answer: 4. Non-contact force

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Question 24. In an ecosystem, if there are 40,000 kg of producers, how many kg of tertiary consumers are there?

1. 4 kg
2. 40 kg
3. 400 kg
4. 4000 kg

Answer: 2. 40 kg

Question 25. What type of energy is produced at the time of clapping?

1. Sound energy
2. Chemical energy
3. Magnetic energy
4. All of these

Answer: 1. Sound energy

Question 26. Between two balls weighing 10 kg and 20 kg, which one would experience more friction?

1. 10 kg ball
2. 20 kg ball
3. Same for both
4. None of the above

Answer: 2. 20 kg ball

Question 27. Kicking a football is

1. Pull
2. Push
3. Impulse
4. Throw

Answer: 3. Impulse

Question 28. An example of a renewable source of energy is

1. Coal
2. Natural gas
3. Petroleum
4. Tidal energy

Answer: 4. Tidal energy

Question 29. Blowing of electric horn involves the transformation of

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1. Mechanical energy to sound energy
2. The heat energy to sound energy
3. Electrical energy to sound energy
4. Chemical energy to sound energy

Answer: 3. Electrical energy to sound energy

Question 30. An example of force without touch is

1. Nuclear force
2. Magnetic attraction
3. electrostatic repulsion
4. all of these

Answer: 4. All of these

Chapter 6 Primary Concept Of Force And Energy Fill In The Blanks

Question 1. Cobalt and magnet __________ each other.
Answer: Attract

Question 2. Coal, petroleum, and natural gases are known as __________ energy.
Answer: Non-renewable

Question 3. The gravitational force acting on a body is called it’s __________
Answer: Weight

Question 4. While closing the zip of your school bag, you apply __________ force.
Answer: Pulling

Question 5 The smoother the surface, the less the __________
Answer: Friction

Question 6. Energy flow in the ecosystem is __________
Answer: Unidirectional

Question 7. Interconnected food chains are called __________ __________.
Answer: Food web

Question 8. Only __________ % of energy is taken at each trophic level of the energy pyramid.
Answer: 10

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Question 9. Complete the food chain Paddy Rat→ __________ →Hawk.
Answer: Snake

Question 10. The object which changes its position with respect to time is called a ______________object.
Answer: Moving

Question 11. The capacity of a body to do work is called __________.
Answer: Energy

Question 12. __________ and __________ energy are forms of mechanical energy.
Answer: Potential, Kinetic

Question 13. __________ converts solar energy into electrical energy.
Answer: Solar Photovoltaic Cells

Question 14. During photosynthesis, __________ energy is transformed into energy.
Answer: Light, Chemical

Question 15. The lowest trophic level of the food pyramid is composed of __________
Answer: Producers

Chapter 6 Primary Concept Of Force And Energy Identify As True Or False

Question 1. Aluminum and copper are magnetic substances.
Answer: False

Question 2. Friction acts in the same direction as the impressed force which causes motion.
Answer: False

Question 3. Wind and tidal energy are renewable sources of energy.
Answer: True

Question 4. In the Sl system, a unit of force is done.
Answer: False

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Question 5. Friction is associated with disadvantages only.
Answer: False

Question 6. Most forms of energy can be converted into other forms of energy.
Answer: True

Question 7. Green plants belong to the tertiary trophic level of the food chain.
Answer: False

Question 8. Running water produces hydel energy.
Answer: True

Question 9. The description of motion is independent of the location of the viewer.
Answer: False

Question 10. If friction is absent, a moving ball shall continue to roll forever along a straight line.
Answer:

Question 11. Push can act through the non-rigid connector.
Answer: False

Question 12. There are 8 forms of energy prevalent in nature.
Answer: True

Question 13. Push and pull are contact forces.
Answer: True

Question 14. The apex of the food pyramid involves more energy than the base.
Answer: False

Question 15. Wood is a type of non-renewable source of energy.
Answer: True

Chapter 6 Primary Concept Of Force And Energy Match The Columns

Answer: A-1,B-3,C-4,D-2

Answer: A-4,B-1,C-2,D-3

Answer: A-3,B-4,C-2,D-1

Answer: A-5,B-1,C-2,D-4

Chapter 6 Primary Concept Of Force And Energy Answer In Words Or A Sentence

Question 1. What % of energy is absorbed in each trophic level?
Answer: 10% energy.

Question 2. Does friction depend on the area of the surface in contact with each other?
Answer: No.

Question 3. How is each food level in a food pyramid known?
Answer: Trophic level.

WBBSE Class 6 Science Question Answer

Question 4. Who formulated the concept of the 10 percent law?
Answer: Raymond Lindemann.

Question 5. What is the unit of weight in the CGS system?
Answer: Dyne.

Question 6. Which one is more stable-food chain or the food web?
Answer: Food web.

Question 7. Give an example where chemical energy is transformed into heat, light, and sound energy.
Answer: Bursting of cracker.

Question 8. Give two examples of fossil fuels.
Answer: Coal and petroleum.

Question 9. What type of force is involved while we take out a drawer?
Answer: Pull.

Question 10. What do the animals which live on plants known as?
Answer: Herbivores.

Question 11. Choose the odd one out-tiger, dog, cow, leopard.
Answer: Cow (herbivores); others are carnivores.

Question 12. Sort out the magnetic substance-wood, plastic, kerosene, cobalt.
Answer: Cobalt.

Question 13 Mention two devices that convert solar energy.
Answer: Solar cooker and solar lantern.

Question 14. What is the SI unit of friction?
Answer: The SI unit of friction is Newton.

Question 15. State the type of energy transfer that occurs when window panes break due to an explosion.
Answer: Chemical energy to mechanical energy.

Question 16. State the type of energy transfer that occurs when we hear a radio broadcast of a cricket match.
Answer: Electrical energy to sound energy

Question 17. Which organisms come last in each trophic level?
Answer: Detrivores and decomposers (ex: Dung beetles, fungi, bacteria, etc.)

Question 18. Which trophic level consists of the greatest number of organisms?
Answer: First trophic level or Producers.

Question 19. What is the force that is responsible for wearing out of bicycle tires?
Answer: Frictional force of road.

Question 20. What is the direction of the force of friction acting on a moving object?
Answer: Opposite to the direction of motion.

Chapter 6 Primary Concept Of Force And Energy Short Answer Type Questions

Question 1. Arrange in order: rain, water, cloud, vapor.
Answer: Water vapour→ cloud→rain.

Question 2. Give an example where the force of friction is advantageous to us and explain it.
Answer: Friction helps us in walking. When a man walks, he lifts one leg up, leans forward, and with the other leg presses the ground in a slightly inclined fashion in the backward direction.

The pressing of the leg is balanced by the frictional force of the ground, otherwise, he will slip and fall forward on his face. Thus friction prevents him from slipping.

WBBSE Class 6 Science Question Answer

Question 3. Current is drawn from the following devices(a) a Generator and (b) A dry cell. State the energy transformation taking place in each case.
Answer:

1. In a generator, mechanical energy changes into electrical energy.
2. A dry cell converts the stored chemical energy into electrical energy.

Question 4. How do contact forces act?
Answer: Contact forces are to be applied through something rigid or non-rigid. Push is applied through something rigid while a pull can act through a non-rigid connector, such as a rope or a wire.

Question 5. What is mechanical energy?
Answer: Kinetic and potential energies are together known as mechanical energy. It is the energy associated with the motion and position of an object.

Question 6. What is the water cycle?
Answer: The water cycle is the cycle of processes by which water circulates between the earth’s water bodies, atmosphere, and land involving evaporation, transpiration, condensation, and precipitation.

Question 7. What are the causes of the energy crisis?
Answer: The causes of the energy crisis may be briefly summarised as

1.  Increase in population and rapid urbanization leading to overconsumption
2.  Increase in automobiles
3. Growing needs of industries and mechanized agriculture.
4. The decline of stored fossil fuels.
5. Poor infrastructure, flaws in the distribution network, and wastage
6. Miscellaneous factors like war, natural calamities, etc

Question 8. What are magnetic substances?
Answer: Materials that can be magnetized and which are strongly attracted to a magnet are called magnetic substances. These include iron, cobalt, lodestone, etc.

Question 9. Arrange the following organisms in the correct sequence from producer to secondary consumer
Kingfisher-algae-fish.
Answer: The correct sequence shall be-
algae (producer) fish (primary consumer) → kingfisher (secondary consumer).

Question 10. Suppose you are traveling in a bus or train. When the bus or train is in motion, which objects would appear to be at rest to you?
Answer: When an observer is inside a moving train, then the compartment itself along with its fixed components (such as berths, seats, window frames, etc.) and the passengers who are seated inside the compartment shall appear stationary to the observer.

Question 11. Name a force that causes the dissipation of energy. On what factors does this force depend?
Answer: Friction causes the dissipation of energy in the form of heat.

The factors on which friction depends are:

1. Friction depends on the material and the nature of the surfaces in contact and their state of polish.
2. Friction depends upon the mass of the body because that in turn determines how the surfaces in contact are pressed together.

Question 12. Friction is independent of area. But brakes of very small contact areas are not used. Why?
Answer: It is true that friction does not depend on the area of contact but it causes a lot of wear and tear.

WBBSE Class 6 Science Question Answer

Thus brakes have to be built with appreciable contact areas to avoid wear and tear and to increase the life span of the brake shoe or pad.

Chapter 6 Primary Concept Of Force And Energy Long Answer Type Questions

Question 1. Define force. What is its unit in the Sl system? State any two effects of force.
Answer: A force may be defined as an external cause that changes or tends to change the state of rest or of the uniform motion of a body in a straight line.

In the Sl system, the unit of force is called Newton. Two effects of force are

1. It can set a stationary body into motion.
A railway engine can move a stationary train by applying a pull or push.

2. It can stop a moving body.
A speeding car is stopped by the application of brakes.

Question 2. ‘Sun is the ultimate source of all energies available on earth’ discuss.
Answer: When a man walks, he lifts one leg up, leans forward, and with the other leg presses the ground in a slightly inclined fashion in the backward direction.

Question 3. What is a pyramid of energy? Why is there the highest amount of energy at the base and the lowest at the apex of an energy pyramid?
Answer: The Push is applied through something rigid while a pull can act through a non-rigid connector, such as a rope or a wire.

Question 4. What is friction? Give examples (one each) of the following
1. friction produces heat
2. friction causes wear and tear of mating surfaces.
Answer:

1. Friction produces heat:

1. When two palms are rubbed together, they become warm.
2. If a stone is rubbed on a metallic surface for some time, the metal becomes hot.
3. When we want to ignite a matchstick, we rub the stick on the rough surface of a matchbox.

The rough surface of the matchbox and the head of the matchstick both contain gunpowder on them. Rubbing causes the temperature to increase and heat is produced which ignites the matchstick.

2. Friction causes erosion of contact surfaces:

1. The tires of cars or cycles get eroded after a long run.

Question 5. State the differences between renewable and non-renewable sources of energy.
Answer:

Question 6. Explain the 10 percent law in connection with the energy pyramid.
Draw a food chain with respect to energy flow in a commonly formed ecosystem formed of the organisms named below
(1) Hawk (2) Grasshopper (3) Grass (4) Snake (5) Toad.
Answer: According to the 10 percent law, about 10% of total energy is transmitted during energy flow through several trophic levels to be used up for building the body mass, and rest is dissipated as heat energy.

For example, 100 kg biomass in the grass will make 10 kg biomass for herbivorous animals (ex. deer) and 1 kg Primary Concept of Force and Energy Grass Grasshopper→Toad Snake→Hawk.

Question 7. When a ball is thrown vertically upward, how do its potential and kinetic energy change?
Answer: At the moment when the ball is thrown, it has only kinetic energy due to an upward velocity. As it attains height, it loses kinetic energy because its velocity decreases and gains potential energy.

WBBSE Class 6 Science Question Answer

At the highest point of ascent, the ball stops momentarily possessing potential energy only. During descent, it loses potential energy and gains kinetic energy as its velocity increases with time.

Just before touching the ground, the ball possesses kinetic energy only.

Question 8. A solar cooker is turned ON. Which type of energy conversion is taking place here? Name two possible measures to mitigate the global energy crisis.
Answer: When a solar cooker is turned ON, light energy is converted into heat energy.
Two steps to mitigate the global energy crisis:

1. Higher utilization of renewable types of energy in a planned manner.

2. Prevention of wastage of energy in daily urban life.

Question 9. How does the transfer of energy take place in the water cycle?
Answer: Solar energy causes surface water to undergo evaporation to become water vapor. As the water vapor attains height it gains potential energy.

Once water vapor is in the upper part of the atmosphere, it releases heat to the surrounding colder air to either condense into liquid or form ice crystals.

Air currents move the clouds across the planet. The water droplets in clouds collide with other droplets to form larger droplets and undergo precipitation as rain or snowfall under the influence of gravity.

As it falls it gains kinetic energy. Kinetic energy drives runoff water that flows downhill through streams, rivers, and lakes.

Some of the water eventually reaches the oceans and again participates in the water cycle.

Thus it is self-renewing and continuous and the sun provides all the energy to cause the change of states through the processes of melting, sublimation, evaporation, freezing, condensation, and deposition.

Chapter 5 Measurement Review Questions Environment Review Questions MCQs

Question 1. The SL system has a number of elementary fundamental units.

1. 6
2. 7
3. 8
4. 9

Answer: 2. 7

Question 2. An example of a fundamental quantity is

1. Volume
2. Velocity
3. Height
4. Area

Answer: 3. Height

Read And Learn More: WBBSE Solutions For Class 6 School Science

Question 3. The SI unit of volume is

1. cm/s
2. m/s2
3. cc
4. cubic metre

Answer: 4. cubic metre

Question 4. Which of the following physical quantities does not have a unit?

1. Mass
2. Specific gravity
3. Volume
4. Current

Answer: 2. Specific gravity

Question 5. Which among the following is not a fundamental quantity?

1. Temperature
2. Mass
3. Intensity of light
4. Density

Answer: 4. Density

WBBSE Class 6 Science Question Answer

Question 6. The quantity of atoms or molecules has the unit of

1. kg
2. cc
3. mole
4. g

Answer: 3. mole

Question 7. The biggest unit of length is

1. Parsec
2. Angstrom
3. Kilometre
4. Micron

Answer: 1. Parsec

Question 8. A light year is a unit of

1. Time
2. Intensity of light
3. Temperature
4. Density

Answer: 4. Density

Question 9. Common balance measures

1. Weight
2. Mass
3. Density
4. Volume

Answer: 2. Mass

Question 10. The most accurate model of the timekeeper is

1. Stop-watch
2. Atomic clock
3. Wrist-watch
4. Digital clock

Answer: 2. Atomic clock

Question 11. The common instrument employed to measure the growth of plants is

1. Stop-watch
2. Centimetre scale.
3. Measuring cylinder
4. Auxanometer

Answer: 4. Auxanometer

Question 12. A measuring cylinder can be used to measure the volume of

1. Liquid only
2. Solid only
3. Both liquid and solid
4. None of the above

Answer: 3. Both liquid and solid

Question 13. 1 mean solar day =.minutes.

1. 1440
2. 24
3. 60
4. 86400

Answer: 1. 1440

Question 14. The smallest division of a metre scale is

1. 1 m
2. 1 cm
3. 1 dm
4. 1mm

Answer: 4. 1mm

WBBSE Class 6 Science Question Answer

Question 15. Time is defined as

1. Starting an event
2. Ending of an event
3. The interval between two events
4. None of the above

Answer: 3. Interval between two events

Question 16. The volume of 1 L of water is

1. Less than 1 cubic decimetre
2. Greater than 1 cubic decimetre
3. Equal to 1 cubic decimetre
4. Equal to 100 cubic centimetres

Answer: 3. Equal to 1 cubic decimetre

Question 17. Which is not a unit of area?

1. Square cm
2. Square metre
3. M/S
4. Square km

Answer: 3. M/S

Question 18. Your body weight is 30 kg, i.e.ing.

1. 300
2. 3000
3. 30,000
4. 3

Answer: 3. 30,000

Question 19. Hour is a

1. fundamental unit
2. derived unit
3. number
4. none of the above events of short duration

Answer: 2. derived unit

WBBSE Class 6 Science Question Answer

Question 20. Time pertaining to an

1. Wrist-watch
2. Sundial
3. Wall clock
4. Stop-watch

Answer: 4. stop-watch

Question 21. Angstrom is the unit of

1. Mass
2. Length
3. tTme
4. Current

Answer: 2. length

Question 22. The rate of growth is

1. Growth/time
2. Time/growth
3. Growth x time
4. Time

Answer: 1. Growth/time

Question 23. A standard unit should be

1. Of convenient size to use
2. Fixed under any conditions of space and time
3. Defined without doubt
4. All of the above

Answer: 4. All of the above

Question 24. The area of the rectangular surface is

1. Length x  Breadth
2. Length +  Breadth
3. Length/Breadth
4. 2 x (Length + Breadth)

Answer: 1. Length x Breadth

Question 25. In MKS system, K stands for

1. Kelvin
2. Kilometre
3. Kilogram
4. None of the above

Answer: 2. Kilometre

WBBSE Class 6 Science Question Answer

Question 26. A glass is filled to the brim with water. When you immerse one of your fingers into it, some amount of water is spilt out. Which parameter among the following is the same for the water that is spilt out and the immersed portion of the finger?

1. mass
2. length
3. weight
4. volume

Answer: 3. volume

Question 27. Using a digital stop-watch, we can measure time upto

1. 0.1s
2. 0.01s
3. 0.2s
4. 0.02s

Answer: 2. 0.01s

Question 28. To express your weight, which unit among the following should you use?

1. quintal
2. mg
3. kg
4. g

Answer: 3. kg

Question 29. An incorrect estimate is

1. overestimate
2. underestimate
3. both
4. none

Answer: 3. both

Class 6 WBBSE Science Question Answer

Question 30. Among the following, the pair having the same unit is

1. energy and work
2. volume and density
3. force and energy
4. work and power

Answer: 1. energy and work

 

Chapter 5 Measurement Fill In The Blanks

Question 1. The space occupied by any substance is called ___________
Answer:  Volume

Question 2. Mass/Volume= ___________
Answer:   Density

Question 3. 1 litre = ___________ CC.
Answer:  1000

Question 4. SI unit of time is ___________
Answer:  Second

Question 5. To measure the length of your classroom you may use ___________
Answer: Measuring tape

Question 6. Everything which can be measured is called a ___________
Answer: Physical quantity

Question 7. Sl unit of temperature is ___________
Answer: Kelvin

Question 8. A scale having a length of one metre is called a ___________ scale.
Answer: Metre

Question 9.  Cubic centimetre is the unit of ___________
Answer: Volume

Question 10.  An estimate that exceeds the actual is called an ___________
Answer: Overestimate

Class 6 WBBSE Science Question Answer

Question 11.  Growth is attended by ___________ in weight.
Answer: Increase

Question 12. 1 second = ___________ part of an hour.
Answer: 1/3600

Question 13. The volume of liquid is usually expressed in ___________
Answer: Litre

Question 14. Temperature is a ___________ physical quantity.
Answer: Fundamental

Question 15. 10 dm is equal to ___________ metre.
Answer: 1

Question 16. The unit of mass in the FPS system is ___________
Answer: Pound

Question 17. Velocity is a ____________unit.
Answer: Derived

Question 18. ___________units are a combination of one or more fundamental units.
Answer: Derived

Question 19. The height of a person is measured with ___________
Answer: Centimetra scale

Question 20. An informal estimate when very little information is available is called a ___________
Answer: Guesstimate

Question 21. If the area is sq. cm, then ___________ → century.
Answer: Time

Question 22. If length scale, the volume of liquid → ___________.
Answer: Measuring cylinder

Question 23. To measure the purity of gold, ___________ is used.
Answer: Carat

Question 24. The interval between the start of an event and its completion is called ___________
Answer: Time

Question 25. There are ___________ elementary or fundamental units in Sl system of measurement.
Answer: Seven

Class 6 WBBSE Science Question Answer

Chapter 5 Measurement Identify As True Or False

Question 1. A light year is a fundamental unit
Answer: True

Question 2. Precise measurement is not very important in our daily lives.
Answer: False

Question 3. The surface area of a sphere = × diameter x diameter.
Answer: True

Question 4. We can use a stopwatch instead of a wristwatch to see the time.
Answer: False

Question 5. Length, mass and time are derived units.
Answer: False

Question 6. Growth in animals takes place throughout life.
Answer: False

Question 7. Estimation is an approximation.
Answer: True

Class 6 WBBSE Science Question Answer

Question 8. A common balance gives a direct measurement of mass.
Answer: False

Question 9. Millimetre is a sub-multiple of Metre.
Answer: True

Question 10. All the physical quantities have separate units.
Answer: False

Question 11. The fundamental unit of current is Ampere in the SI system.
Answer: True

Question 12. Derived physical units are more number than fundamental units.
Answer: True

Question 13. Bamboo shoots grow rapidly.
Answer: True

Question 14. The area is a fundamental quantity.
Answer: False

Question 15. 1 Mean solar day = 86400 seconds.
Answer: True

Question 16. Direct measurement of the volume of liquid can be done by using a measuring cylinder.
Answer: True

Question 17. All the systems of units have a common unit of time.
Answer: True

Question 18. In the MKS system, M stands for milligram.
Answer: False

Question 19. There are 7 derived physical quantities in the SI system.
Answer: False

Question 20. One litre of milk is equivalent to 1000 cc of milk.
Answer: True

Question 21. Velocity = Distance/Time.
Answer: True

Class 6 Science Question Answer WBBSE

Question 22. Atomic weight has no unit.
Answer: True

Question 23. A cubit is a standard unit.
Answer: False

Question 24. Growth is accompanied by a reversible change of structure or form.
Answer: False

Question 25. A scale may have different lengths.
Answer: True

 

Chapter 5 Measurement Match The Columns

 

Answer: A-2,B-4,C-1,D-3

 

Answer: A-4,B-3,C-1,D-2

 

Answer:

 

Answer:

 

Chapter 5 Measurement Answer In Words Or A Sentence

Question 1. Mention two physical quantities which have the same unit.
Answer: Work and energy.

Question 2. What is the unit associated with the measurement of the mass of a molecule?
Answer: Mole.

Question 3. What is the relation between hectometre and metre?
Answer: 1 hm = 100 m.

Question 4. Which unit is used to measure sub-atomic distances?
Answer: Fermi is used.

Class 6 Science Question Answer WBBSE

Question 5. How does a mason give us measurements of things he needs before starting any construction work?
Answer: By estimation.

Question 6. What is the instrument employed to measure the growth of animals?
Answer: The centimetre scale is used to measure the growth of animals.

Question 7. How many seconds are there in a mean solar day?
Answer: 1 mean solar day = 86400 seconds.

Question 8. Which unit would you prefer to use to measure the distance between two cities-kilometre or metres?
Answer: Kilometre.

Question 9. How many fundamental physical quantities are there as per the Sl system?
Answer: Seven fundamental physical quantities are there as per the Sl system.

Question 10. What type of quantity is the intensity of light?
Answer: Fundamental physical quantity.

Question 11. I am a derived unit. In order to compute my value, mass is to be divided by volume. Who am I?
Answer: Density(\(=\frac{Mass}{Volume}\))

Question 12. Find the odd one out Length, time, volume, mass.
Answer: Volume: It is a derived quantity while others are fundamental quantities.

Question 13. Give an example where one has to necessarily take the help of estimation to do work.
Answer: Getting hold of a cricket ball by a fielder when he jumps near the boundary line.

Question 14. What type of measuring device would you use to measure the girth of a tree?
Answer: A measuring tape.

Question 15. What is the biggest unit of time?
Answer: Century = 100 years.

 

Chapter 5 Measurement Qshort Answer Type Questions

Question 1. A body measures 25 m. State the unit and the magnitude of the unit in the statement.
Answer: The statement of a physical quantity (length) shows that the unit is the metre and the magnitude is 25.

Question 2. Define fundamental unit. Name the fundamental units of mass, length, time, current and temperature.
Answer: There are some physical quantities which do not depend on other physical quantities, e.g. length, mass, time, etc.

Class 6 Science Question Answer WBBSE

These physical quantities are called fundamental physical quantities and the units associated with them are called fundamental units. These are independent of any other units.

 

Question 3. Why is the unit of volume a derived unit?
Answer: Volume = length x breadth x height.
The fundamental unit of length appears thrice in the formula of volume i.e. volume is the cube of length. Hence it is a derived unit.

Question 4. Name the convenient unit you would use to measure-
Answer:

1. length of a hall
2. width of a book
3. diameter of a hair
4. distance between two cities

 

 

Question 5. Define time. Express minute as a part of a mean solar day.
Answer: The interval between any two incidents is called time.

1 minute = 1/1440 mean solar day.

Question 6. What do we measure with the help of a thermometer?
Answer: We measure the temperature of a substance with the help of a thermometer.

Question 7. What is a metre scale?
Answer: If the length of the scale is one metre it is called a metre scale.

Question 8. What do the longer and shorter arms of a stopwatch measure?
Answer: The longer hand of a stopwatch records time in seconds with fractions and the shorter one in minutes.

Class 6 Science Question Answer WBBSE

Question 9. State the units in which mass is measured in (i) the CGS system and (ii) the Sl system.
Name the most convenient unit of mass you will use to measure-
Answer:

1. Mass of a small amount of medicine.
2. The bag of sugar.
3. Mass of a cricket ball.
4. The CGS unit of mass is gram (g) and that in the SI system is the kilogram (kg).

 

 

Question 10. Do ratios have units?
Answer: Ratios do not have units. They are unitless physical quantities.

Question 11. Give one example for each of the derived physical quantities having one or two fundamental physical quantities.
Answer: Area (length x breadth) has one fundamental physical quantity.
Velocity (distance/time) has two fundamental physical quantities.

Question 12. Can the volume of a lump of sugar candy be measured with water in a measuring cylinder?
Answer: The lump of sugar would gradually dissolve in water when it is dipped inside water in a measuring cylinder. Hence its volume can not be measured with water.

Question 13. You are given a flexible wire of 10 cm in length. How would you measure a length of 1 m 5 cm with that?
Answer: 1 m is a multiple of 10 cm, since 1 m= 100 cm. Hence, 10 times the full length of the wire measures 1 m.

Since the length of the wire is 10 cm, if it is folded to half, the length of folded wire equals 5 cm. So the measurement involves 10 full lengths of the wire and one-half length of the wire.

Question 14. A bottle of juice holds 750 ml of juice. Can two such bottles be poured into a jar measuring 2000 cc?
Answer: One bottle holds 750 ml.
.: Two bottles hold (750×2) ml =1500 ml = 1500 cc
Since the capacity of the jar is 2000 cc, hence the two bottles can be poured into it.

Question 15. A 30cm scale has one end broken. The mark at
the broken end is 2.6 cm. While measuring the length of a pencil, one end is touched with a 2.6 cm mark and the other end touches the 18.1 cm mark. What is the length of the pencil?
Answer: Length of pencil = (18.1-2.6) cm= 15.5 cm = 155 mm

Question 16. What are the components of the bar on which ‘metre’ is depicted?
Answer: The bar is made of an alloy consisting of 90 per cent platinum and 10 per cent iridium.

 

Chapter 5 Measurement Long Answer Type Questions

Question 1. Define measurement. What is the unit? Do all physical quantities have units?
Answer: The average of the varying solar days over a period of 365 days is called the mean solar day.

Question 2. How would you measure the length of a curved line with a thread and an ordinary ruler?
Answer: A piece of thread is taken. A required portion of the thread is very carefully laid over the given curved line such that the thread completely hides the whole stretch of the line.

Now the length of the straightened part of the thread that was used just to cover up the given line is measured with the help of the ruler which gives the length of the given curved line.

Question 3. How will you measure the rate of plant growth?
Answer: A required portion of the thread is very carefully laid over the given curved line such that the thread completely hides the whole stretch of the line.

Question 4. What is Mean Solar Day? How would you derive the concept of second from it?
Answer: The average of the varying solar days over a period of 365 days is called the mean solar day. When the average or mean solar day is divided by 24, we get 1 hour.

Similarly, dividing 1 hour by 60 we get 1 minute and further dividing this 1 minute by 60, we get 1 second.
Thus,
1 Mean solar day = 24 hours = 24 x 60 minutes = 1440 minutes = 1440 x 60 seconds
= 86400 seconds.
This second is the SI unit of time equal to
1/86,400 of a mean solar day.

Question 5. Explain how a stopwatch work.
Answer: A stopwatch is used to note the time of an event of short duration. It can record 1/5th or even 1/ 10th of a second.

The longer hand records time in seconds with fractions and the shorter one in minutes. There is a press button which, when pressed, starts the watch and if pressed for the second time, stops the watch.

If again the button is pressed, the second and the minute hands return to their own zero mark.

Thus this watch can be started or stopped by pressing its press button just at the beginning and at the end of an event like a race in sports.

Question 6. How would you measure the mass of a substance?
Answer: The mass of a substance is measured indirectly with the help of common balance.

The substance of unknown mass is to be kept on the left scale pan of the common balance and standard known masses in the right scale pan.

When the pointer comes to equilibrium, the mass of the substance is measured as equal to the known standard masses.

Question 7. How can you find the thickness of a single strand of hair?
Answer: Take a single strand of hair and twist it around a pencil very closely together say 30 times. Measure the length of the total number of twists with a scale.

If the length is x cm, then the thickness of a single strand shall be =x/30 cm.

Question 8. You have got a common balance, a kg weight and a sack of rice. How can you measure the mass of 250 g of rice with the help of the common balance and the one kg weight?
Answer: First we measure 1 kg of rice with the help of one kg weight.

Then one kg weight is removed from the right scale pan and the 1 kg rice from the left scale pan is distributed equally among the right and left scale pans till the pointer comes to equilibrium.

At this point, we have 500 g of rice on both scale pans.

Next rice from one scale pan is to be removed and the above process is to be repeated once again to get 250 g of rice in each of the scale pans.

Question 9. If two boys measure the length of the classroom with their hands, will they get the same result? The water level in a measuring cylinder shows a reading of 12.4 ml. A marble is placed inside it and the reading shows 20.2 ml. What is the volume of the marble?
Answer: Handspan or cubit cannot be used as a standard unit of length. The cubit could vary considerably due to the different sizes of handspan of people.

This results in inaccurate values which is the biggest limitation. Thus the two boys would get different results depending on their handspans.

They should use a measuring tape to correctly measure the length of their classroom.

When completely immersed in water, the marble shall dispense a volume of water which is equal to its own volume. 1st reading = 12.4 ml 2nd reading = 20.2 ml
.: Volume of marble=(20.2-12.4) ml 7.8 ml

Question 10. Mention two significances of estimation. Mention three examples from our daily life where we are forced to adopt estimation. Significances of estimation.
Answer: 1. Estimation helps to obtain approximate knowledge about quantities when other resources are not available.
2. it helps to plan ahead and obtain approximate knowledge about the quantities which are otherwise very difficult to measure precisely.

Instances in our daily life where we estimate:

1. While measuring and adding spices, oil etc into food matters during cooking

2. While touching somebody’s forehead to

Class 6 Science Question Answer WBBSE Chapter 4 Rocks And Minerals Review Questions Environment Review Questions MCQs

Question 1. The first formed rock on the earth’s surface is

1. Sedimentary rock
2. Igneous rock
3. Metamorphic rock
4. None of these

Answer:  2. Igneous rock

Question 2. When the earth was created it was made up of

1. Molten rock
2. Solid rock
3. Gas
4. None of these

Answer: 1. Molten rock

Read And Learn More: WBBSE Solutions For Class 6 School Science

Question 3. The rock that is formed by the cooling and solidification of lava or magma is called

1. Metamorphic rock
2. Sedimentary rock
3. Igneous rock
4. None of these

Answer: 3. Igneous rock

Question 4. The hot molten rock material found deep inside the earth is called

1. Lava
2. Magma
3. Pyroclast
4. None of these

Answer: 2. Magma

Question 5. When magma comes out of a crater or vent of a volcano, it is called

1. Magma
2. Lava
3. Ash
4. All of these

Answer: 2. Lava

Class 6 Science Question Answer WBBSE

Question 6. As we go deeper into the earth’s crust the temperature and pressure

1. Increase
2. Decrease
3. Remain same
4. Decrease suddenly

Answer: 1. Increase

Question 7. An example of igneous rock is

1. Sandstone
2. Marble
3. Limestone
4. Granite

Answer: 4. Granite

Question 8. The stone found near the railway tracks is

1. Granite
2. Basalt
3. Marble
4. Pumice

Answer: 2. Basalt

Question 9. When bubbling foam at the top of hot magma

1. Granite
2. Basalt
3. Pumice
4. Sandstone

Answer: 3. Pumice

Question 10. The deposition and subsequent cementation of sediments within water bodies help to form

1. Igneous rock
2. Sedimentary rock
3. Metamorphic rock
4. None of these

Answer: 2. Sedimentary rock

Question 11. An example of sedimentary rock is

1. Pumice
2. Sandstone
3. Slate
4. Basalt

Answer: 2. Sandstone

Question 12. Fossils are found in

1. Sedimentary rocks
2. Igneous rocks
3. Metamorphic rocks
4. All of these

Answer: 1. Sedimentary rocks

Question 13. Marble is a type of metamorphic rock formed from

1. Granite
2. Sandstone
3. Limestone
4. Basalt

Answer: 2. Sandstone

Class 6 Science Question Answer WBBSE

Question 14. The metal that develops a red-coloured rust, if it remains exposed to air and moisture is

1. Copper
2. UIron
3. Aluminium
4. None of these

Answer: UIron

Question 15. A metal that is found as a compound in nature is

1. Mica Es
2. Gold
3. Copper
4. None of these

Answer:  3. Copper

Question 16. When metals are found as compounds mixed with sand and soil in nature, they are called

1. Rocks
2. Minerals
3. Non-metals
4. None of these

Answer: 2. Minerals

Question 17. The type of mineral from which metals can be extracted easily and profitably is called its

1. Ore
2. Alloy
3. Atom
4. Extract

Answer: Ore

Question 18. An ore of iron is

1. Bauxite
2. Copper glance
3. Haematite
4. Augite

Answer: 3. Haematite

Question 19. Bronze is a mixture of

1. Copper and zinc
2. Copper and iron
3. Copper and tin
4. Copper and gold

Answer: 3. Copper and tin

Question 20. Chromium mixed with iron forms

1. Bronze
2. Stainless steel
3. Brass
4. Bell-metal

Answer: 2. Stainless steel

Question 21. The impressions or rocky remains of once-living organisms are called

1. Fossils
2. Minerals
3. Metals
4. None of these

Answer: 1. Fossils

Question 22. The materials that are burnt to produce heat are called

1. Rocks
2. Minerals
3. Fuels
4. None of these

Answer: 3. Fuels

Question 23. Coal, petroleum and natural gas are called

1. Fossil fuels
2. Black fuel
3. Rock fuels
4. None of these

Answer: 1. Fossil fuels

Class 6 Science Question Answer WBBSE

Question 24. When coal is heated at high temperatures in the absence of oxygen, a substance is produced called

1. Rock oil
2. Coke
3. Coal tar
4. None of these

Answer: 2. Coke

Question 25. The full form of LPG is

1. Liquid Petroleum Guard
2. Liquefied Petroleum Gas
3. Less Polluted Gas
4. None of these

Answer: 2. Liquefied Petroleum Gas

Question 26. Which one is not a fossil fuel?

1. Coal
2. Natural gas
3. Petroleum
4. Hay

Answer: 4. Hay

Question 27. Find the odd one among

1. Granite
2. Pumice
3. Limestone
4. Basalt

Answer: 3. Limestone

Question 28. Refining means

1. Extracting natural gas
2. Separation of various fractions of petroleum
3. Burning of coal
4. Sedimentation of fossil fuel

Answer: 2. Separation of various fractions of petroleum

Question 29. Fossil fuels are derived from which of the following sources?

1. Organic matter trapped in sedimentary rock
2. Non-organic matter trapped in
3. Organic matter trapped in igneous rock
4. Organic matter on the crust surface

Answer: 1. Organic matter trapped in sedimentary rock

Class 6 WBBSE Science Question Answer

Question 30. For fossils to form, the organic remains must be covered quickly by

1. Scavengers
2. Lava
3. Water
4. Sediment

Answer: 4. Sediment

Chapter 4 Rocks And Minerals Fill In The Blanks

Question 1. __________ rocks are formed by the cooling and solidification of lava on the earth’s crust or magma under the earth’s crust.
Answer: Igneous

Question 2. __________ is a type of igneous rock.
Answer: Granite

Question 3. When magma comes out of the __________ of a volcano it is called lava.
Answer: Crater

Question 4. __________ are found in sedimentary rocks.
Answer: Fossils

Question 5. The __________ rocks are found under the earth’s surface and their original character and appearance are greatly altered.
Answer: Metamorphic

Class 6 WBBSE Science Question Answer

Question 6. __________ is the metamorphosed form of granite.
Answer: Gneiss

Question 7. __________ and __________ in nature. are found as compounds
Answer: Iron, aluminium

Question 8. Metals found as compounds mixed with sand and soil are known as __________
Answer: Minerals

Question 9. The process of separating metals from the minerals is known as __________ __________.
Answer: metal extraction

Question 10. The type of mineral from which metals can be extracted easily and economically is called it’s __________.
Answer: ore

Question 11. A __________ takes place in the process of metal extraction.
Answer: Chemical change

Question 12. __________ and carbon are mixed to obtain steel.
Answer: Iron

Question 13. Brass is formed when __________ and __________ combine.
Answer: Copper, zinc

Question 14. Alloys are much more __________ than a single metal.
Answer: Stronger

Question 15. Alloy is made by __________ two or more
Answer: Melting

Question 16. __________ are the impression or rocky remains of once-living organisms.
Answer: Fossils

Class 6 WBBSE Science Question Answer

Question 17. __________, __________ and __________ are called fossil fuels.
Answer: Coal, petroleum, natural gas

Question 18. Coal is burnt to generate heat which in turn produces __________
Answer: Electricity

Question 19. LPG cylinders mainly contain liquid __________.
Answer: Propane

Question 20. Natural gas usually occurs in the __________ part of an oil trap.
Answer: Uppermost

Chapter 4 Rocks And Minerals Identify As True Or False

Question 1. The full form of CNG is Common Natural Gas.
Answer: False

Question 2. The principal constituent of Natural Gas is methane.
Answer: True

Question 3. Bitumen or Tar is produced from Iron.
Answer: False

Question 4. The naturally occurring sticky mixture of various organic compounds, water and soil is called coal.
Answer: False

Question 5. LPG is commonly known as Liquefied Petroleum Gas.
Answer: True

Question 6. Wood, paper, and hay are not fossil fuels.
Answer: True

Question 7. Fossils are seen in metamorphic rocks.
Answer: False

Question 8. Gold, solder, and electric fuse are common alloys.
Answer: True

WBBSE Class 6 Science Question Answer

Question 9. Alloys are more resistant to corrosion than single metals.
Answer: True

Question 10. Copper glance is the ore of Iron.
Answer: False

Question 11. Bauxite is the ore of aluminium.
Answer: True

Question 12. When a copper utensil is left unused for a long time it develops a red stain on it.
Answer: False

Question 13. Slate is the metamorphosed form of shale.
Answer: True

Question 14. Pumice has holes in it.
Answer: True

Question 15. Magma is the molten rock material found on the earth’s surface.
Answer: False

Chapter 4 Rocks And Minerals Match The Columns

Answer: A-6,B-3,C-1,D-5

Answer: A-3,B-1,C-4,D-2

Answer: A-2,B-5,C-4,D-1

Answer: A-5,B-4,C-6,D-1

Chapter 4 Rocks And Minerals Answer In Word Or A Sentence

Question 1. What are the major types of rocks?
Answer: Igneous rock, sedimentary rock and metamorphic rock.

Question 2. What are igneous rocks?
Answer: Igneous rocks are those which have a fiery origin.

Question 3. How is igneous rock formed?
Answer: Igneous rocks were formed by the cooling and solidification of molten magma under the earth’s crust or lava on the earth’s crust.

Question 4 Name two igneous rocks.
Answer: Granite and Basalt.

Question 5. How can we identify the igneous rock pumice?
Answer: We can see holes in the igneous rock pumice.

Question 6. What are sedimentary rocks?
Answer: Sedimentary rocks are formed by the deposition and subsequent cementation of sediments within the bodies of water like seas, lakes etc.

WBBSE Class 6 Science Question Answer

Question 7. What are the sediments made up of?
Answer: The sediments are actually broken fragments derived from the erosion of primary igneous rocks.

Question 8. How are the layers of sediments compacted to form sedimentary rocks?
Answer: Due to the increase of heat and pressure of the overlying sediments, the underlying sediments get cemented and compacted to form sedimentary rocks.

Question 9. Name two sedimentary rocks.
Answer: Sandstone and Shale.

Question 10. What do we find in the sedimentary rocks?
Answer: Fossils or the rocky remains of dead plants and animals.

Question 11. What causes igneous or sedimentary rocks to change into metamorphic rocks?
Answer: Due to excessive heat and pressure igneous and sedimentary rocks undergo physical and chemical changes to form metamorphic rocks.

Question 12. What are minerals?
Answer: Minerals are naturally occurring solid inorganic, crystalline substances with a definite chemical composition.

Question 13. What is metal extraction?
Answer: The process of separating metals from the mineral (ore) is known as metal extraction.

Question 14. What is an ore?
Answer: The type of mineral from which a metal can be extracted easily and profitably (economically) is known as its ore.

Question 15. What are alloys?
Answer: The homogeneous mixture or combination of different metals or metals with non-metals in a fixed ratio (especially to give strength) is called an alloy. For example, stainless steel is an alloy of chromium and iron.

Question 16. Mention two important characteristics of an alloy.
Answer: Alloys are much stronger than single metals and do not easily respond to chemical reactions.

Question 17. How is an alloy made?
Answer: An alloy is made by melting of two or more elements together, one of which is a metal. The mixture is then cooled to obtain a solid substance called an alloy.

WBBSE Class 6 Science Question Answer

Question 18. What is a fossil?
Answer: The impressions or the rocky remains of once-living organisms are called fossils.

Question 19. Write two uses of fossils.
Answer: Fossils are useful tools for dating rocks and also for showing the long history of life on Earth.

Question 20. Why are coal, petroleum or natural gas called fuels?
Answer: Coal, petroleum and natural gas are called fuels as when they are burnt they produce heat and power.

Question 21. Write one use of coal.
Answer: Coal is burnt to generate heat which in turn produces electricity.

Question 22. Write one use of petroleum.
Answer: Petroleum is widely used as a fuel for automobiles like cars, lorries, motorcycles etc.

Question 23. What is the full form of CNG?
Answer: Compressed Natural Gas.

Question 24. Name the full form of LPG.
Answer: Liquefied Petroleum Gas.

Question 25. What is amalgam?
Answer: An alloy of mercury metal with one or more other metals is known as amalgam. For example, Sodium amalgam is composed of sodium and mercury.

Chapter 4 Rocks And Minerals Qshort Answer Type Questions

Question 1. What is magma?
Answer: Deep inside the earth due to increasing temperature and pressure the rocks remain in a molten state as magma.

Question 2. What is lava?
Answer: When the magma comes out of the cracks of the crust or through the crater (vent) of a volcano it is called lava.

Question 3. How are igneous rocks formed under the earth’s crust?
Answer: Deep inside the earth due to increasing temperature and pressure the rocks remain in a molten state as magma. This magma rises to the surface through cracks of the crust.

While coming out it undergoes changes in temperature and pressure that causes it to cool, solidify and crystalize beneath the surface of the Earth’s crust to form intrusive igneous rocks, e.g. Granite.

Question 4. How are igneous rocks formed above the earth’s crust?
Answer: The magma when it comes out of the cracks of the crust or through the crater (vent) of a volcano is called lava.

This lava cools and solidifies on the earth’s surface quickly to form another kind of igneous rock, known as extrusive igneous rocks, e.g. Basalt.

Question 5. Why are holes seen on the igneous rock pumice?
Answer: Pumice is formed when there is rapid cooling and depressurization.

Holes are usually seen on the pumice stone. These holes are formed when the dissolved gases of the hot magma escape into the air and the froth at the top of the hot magma quickly cools and solidifies.

Question 6. How do the softer sediments under the sea turn into sedimentary rocks?
Answer: Sediments derived from igneous rocks are eroded and transported by the agents of denudation (rain, wind, river, glacier, etc.) and are deposited in layers in the sea. When sedimentation continues the older rock layers become buried deeper.

Over a long period, due to the increase in heat and pressure of the overlying sediments the underlying sediments get compacted and cemented and turn into sedimentary rocks.

Question 7. How do minerals differ from ores? or Why “all ores are minerals but all minerals are not ores”?
Answer: If a metal has more than one mineral form, then it is not necessary that all of them are ores.

For every mineral deposit, there is a set of conditions, such as the level of concentration of the metal and the size of the deposit that the deposit may be worked at a profit.

If a mineral deposit is sufficiently rich to be worked at a profit, it will then be called an ore deposit otherwise not. So, all ore deposits are mineral deposits, but the reverse is not true.

Question 8. Why do metals after extraction look different from their ores?
Answer: Metals, after they are extracted from ores, look different from their ores. This is because a chemical change takes place in the process of metal extraction.

Question 9. Why are most of the metals used today in the form of alloys?
Answer: Today, more than 90% of metals used are in the form of alloys. This is because alloys have many advantages that a single metal does not have.

Alloys are much stronger than a single metal, has the ability to withstand heavy weight, do not readily respond to chemical reactions and are resistant to corrosion.

Question 10. How did the dead bodies of animals come inside the rock and become fossils?
Answer: Millions of years ago the fish, the snail and the sea star were all alive. After the death of these animals, their bodies got buried under water or under the surface of the earth.

The soft fleshy parts of their bodies decayed in the course of time. Soon after the initial decay process, the remains of their bodies got covered with sediments.

The remains after undergoing a variety of physical and chemical changes, got transformed into rocks then. The impressions or rocky remains of once-living organisms are called fossils.

Question 11. What are fossil fuels?
Answer: The materials such as coal, gas or oil that are burnt to produce heat and power are called fuels. Coal, gas and oil are obtained from the remnants or dead remains of plants and animals that lived a long time ago.

These dead remains had undergone changes for millions of years and were transformed into fossils. Hence, coal, petroleum (oil) and natural gas are known as fossil fuels.

Question 12. Why are coal, petroleum and natural gas called fossil fuels?
Answer: Coal, petroleum and natural gas are fuels formed from the dead remains of ancient plants and animals which had undergone changes for millions of years and were transformed into fossils.

Hence, they are called fossil fuels.

Question 13. How is metallurgical Coke produced?
Answer: Coke is produced when coal is heated at a high temperature (about 1100°C) in the absence of oxygen.

Question 14. What is CNG and why is it used widely in our country?
Answer: Compressed Natural Gas or CNG is made when purified natural gas is compressed (put under pressure) and stored in a cylinder and used as fuel.

In our country as well as in many other countries CNG is used to run public transport, especially buses, because it causes less pollution than other commonly used fuels like diesel or petrol.

It is also used as fuel for cooking and power generation.

Question 15. Mention three differences between LPG and
Answer:

WBBSE Class 6 Science Question Answer Chapter 2 Phenomena Around Us Review Questions Environment Review Questions MCQs

Question 1. Which one of the following is a physical change?

1. Curd from milk
2. Rusting of iron
3. Melting of butter
4. X-ray photography

Answer: 3. Melting of butter

Question 2. Which one of the following is a chemical change?

1. Switching on a bulb
2. Digestion of food
3. Boiling of water
4. Inflation of tyre

Answer: 2. Digestion of food

Read And Learn More: WBBSE Solutions For Class 6 School Science

Question 3. In cities, chlorine is mixed with water

1. To kill the germs
2. To colour the water
3. To add a sweet odour to the water
4. None of these

Answer: 1. To kill the germs

WBBSE Class 6 Science Question Answer

Question 4. The tyre of a cycle is inflated with air. This process is a

1. Irreversible process
2. Physical process
3. Chemical process
4. Natural process

Answer: 2. Physical process

Question 5. Melting of ice is an example of

1. Man-made process
2. Irreversible process
3. Physical process
4. Periodic process

Answer: 3. Physical process

Question 6. Identify the chemical change.

1. Burning of magnesium filament in oxygen
2. Mixing of hydrogen and oxygen
3. Sulphuric acid is slowly poured into the water
4. Heating of the metal rim of a cartwheel

Answer: 1. Burning of magnesium filament in oxygen

Question 7. Identify the irreversible change.

1. Melting of wax
2. Green leaves becoming yellow
3. Bending of railway lines during hot summer days
4. Formation of dew drops

Answer: 2. Green leaves becoming yellow

Question 8. Identify which of the following is a non-periodic change.

1. Change of season
2. Tide and ebb
3. Flash flood
4. Leap year

Answer: 3. Flash flood

WBBSE Class 6 Science Question Answer

Question 9. An example of a physical change is

1. Making puffed rice (more) from rice
2. Melting of wax
3. Rusting
4. Yellowing of teeth

Answer: 2. Melting of wax

Question 10. When a candle is lit

1. Only physical changes occur
2. Only chemical changes occur
3. Physical and chemical changes occur simultaneously
4. None of the changes occurs

Answer: 3. Physical and chemical changes occur simultaneously

Question 11. A piece of paper is burnt and reduced to ashes. This is

1. An irreversible change
2. Physical change
3. Periodic change
4. A change that does not need energy

Answer: 1. An irreversible change

Question 12. Which one is a physical change?

1. Melting of glaciers
2. Cataract in eyes
3. Black stains on teeth
4. Ripening of mango

Answer: 1. Melting of glaciers

Question 13. In which case heat energy is liberated?

1. Urea is dissolved in water
2. Sulphuric acid is dissolved in water
3. Ammonium nitrate is dissolved in water
4. Evaporation of spirit

Answer: 2. Sulphuric acid is dissolved in water

Question 14. Identify the process which is natural and irreversible.

1. Ripening of fruit
2. A candle is lit
3. A football is inflated
4. Curd is prepared from milk

Answer: 1. Ripening of fruit

Question 15. Identify the process which is a man-made and chemical process.

1. Dissociation of water by passing electricity through it
2. Growth of a cancer cell
3. The magnetisation of a piece of iron
4. Tadpole transforming into a frog

Answer: 1. Dissociation of water by passing electricity through it

Question 16. A chemical fertiliser among the following is

1. Carbaryl
2. Malathion
3. Dap
4. All of these

Answer: 2. Malathion

Question 17. Identify the desirable, periodic and natural change among the following:

1. Growth of a plant
2. Cleaning activities of the municipality
3. Generation of electricity
4. Rotation of earth

Answer: 4. Rotation of earth

Question 18. Which one among the following is an irreversible physical change?

1. Heating of iron to red hot stage
2. Dissolution of salt in water
3. A glass pot breaking into pieces
4. Water freezing into ice

Answer: 3. A glass pot breaking into pieces

WBBSE Class 6 Science Question Answer Chapter 2 Phenomena Around Us Fill In The Blanks

Question 1. When water is boiled, it is transformed into Vapour. This is a _________ change.
Answer: Physical

Question 2. Earthquake is a __________ and __________ change.
Answer: natural; undesirable

Question 3. __________ is added to water to kill the germs.
Answer: Chlorine

Question 4. To and fro movement of a pendulum is a __________ change.
Answer: periodic

Question 5. Freezing of water is a __________ change.
Answer: Physical

Question 6. Melting of glaciers is a __________ and __________ change.
Answer: natural; physical

Question 7. Taking an X-ray photograph of a fractured bone on an X-ray plate is a __________ change.
Answer: chemical

WBBSE Class 6 Science Question Answer

Question 8. When chemical substances are taken in a solution state, they react __________
Answer: faster

Question 9. When an apple is cut and kept open in the air for sometime __________ stain appears on the exposed surface.
Answer: brown

Question 10. When __________ is dissolved in water __________ is absorbed change.
Answer: urea; heat

Question 11. When ammonium nitrate is dissolved in water, the solution becomes __________
Answer: cold

Question 12. When iron is kept in moist air for a prolonged time, __________ is formed on the iron surface. It is a __________ change.
Answer: rust; chemical

Question 13. Any sort of change (either physical or chemical) involves __________ to be initiated.
Answer: Energy

Question 14. BHC, DDT, malathion etc are commonly used __________
Answer: pesticides

Question 15. The change which involves the formation of one or more new substances having different properties is called a __________ change.
Answer: chemical

Class 6 WBBSE Science Question Answer Chapter 2 Phenomena Around Us Identify As True Or  False

Question 1. Earthquake is an undesirable process.
Answer: True

Question 2. Flood is a periodic and natural change.
Answer: False

Question 3. Excessive use of insecticides is harmful to nature.
Answer: True

Question 4. When an apple is cut and kept open in the air, brown patches appear on the exposed surface. It is a physical process.
Answer: False

Question 5. Yellowing green leaves is a physical process.
Answer: False

Question 6. The preparation of curd from milk is a fast process.
Answer: False

Question 7. The growth of a plant is an irreversible process.
Answer: True

Question 8. Rusting involves the formation of a new compound.
Answer: True

Question 9. When ice cream melts, the heat lost by ice cream is gained by the air. change.
Answer: False

Question 10. Nuclear explosion for scientific purposes is a desired process, but its use in war is highly undesirable.
Answer: True

Question 11. All natural processes are desirable processes.
Answer: False

Class 6 WBBSE Science Question Answer

Question 12. Natural processes occur on their own.
Answer: True

Question 13. Physical processes are always reversible.
Answer: False

Question 14. Physical changes may or may not involve absorption or emission of heat.
Answer: True

Question 15. Chemical processes are always associated with changes in energy.
Answer: True

Question 16. Forest fire is a natural, undesirable, fast process.
Answer: True

Question 17. When a piece of chalk is successively broken into smaller pieces, the total surface area increases.
Answer: True

Question 18. Increased surface area may speed up a chemical change.
Answer: True

Question 19. Rusting of iron is a harmful chemical change.
Answer: True

Question 20. The weakening of our bones within the body is a chemical and physical change.
Answer: False

Chapter 2 Phenomena Around Us match The Column

Answer: A-5,B-1,C-4,D-3

 

Answer: A-3,B-4,C-1,D-2

Answer: A-4,B-5,C-1,D-2

Answer: 1-C-4,2-D-1,3-B-3,4-A-2

Chapter 2 Phenomena Around Us Answer In Words Or A Sentence

Question 1. Plants prepare their own food. What kind of change is it?
Answer: This is a chemical change. In this case, glucose (a new compound) is prepared on the leaves from carbon dioxide and water in the presence of sunlight.

Question 2. Why chlorine is added to water?
Answer: Chlorine is mixed with water to kill the germs present in the water and to remove the smell of water.

Class 6 WBBSE Science Question Answer

Question 3. A mango is ripened. Is it a physical or chemical process?
Answer: It is a chemical process. During ripening new substances are formed within the fruit.

Question 4. Give an example of a process which is a natural, slow and chemical process.
Answer: Ripening of a fruit.

Question 5. Boiling raw rice to prepare boiled rice is a chemical process. -Justify.
Answer: It is a chemical process. During the boiling of raw rice, new substances are formed within it. Also, we cannot get back the raw rice by any means once it is boiled.

Question 6. Give an example of a fast and a slow man-made process.
Answer: The explosion of a bomb is an example of a fast process. Formation of curd from milk is a slow process.

Question 7. A piece of ice is slowly warmed. What type of change it is?
Answer: When a piece of ice is warmed, it melts. This is only a change of state, no new substances are formed. Hence it is a physical change.

Question 8. What do you mean by periodic changes?
Answer: The changes which occur again and again after a fixed interval of time are called periodic changes.

Question 9. Give an example of a natural process which involves a physical change.
Answer: The melting of glaciers is a natural process which involves a physical change.

Question 10. Give an example of a physical process which is reversible.
Answer: Inflating a football.

Question 11. Give an example where both physical and chemical changes occur simultaneously.
Answer: Burning of a candle.

Question 12. Choose the odd one Photosynthesis, rusting, condensation, electrolysis of water
Answer: Condensation: It is a physical change while others are chemical changes.

WBBSE Class 6 Science Question Answer Chapter 2 Phenomena Around Us Qshort Answer Type Questions

Question 1. Which process is called a physical process? Give an example.
Answer: Physical process is a process where no new substances are produced during the process, only the physical state of the matter is changed.

For example, freezing of water into ice is a physical process. Here no new substances are formed, only the state of the matter is changed from liquid state to solid state.

Question 2. When electricity is passed through salted water, which gases are produced? Is it a physical or chemical process?
Answer: When electricity is passed through salted water, hydrogen and oxygen gases are produced. This is a chemical change called the electrolysis of water.

Water is dissociated and two new gases are produced.

Question 3. What will happen if sulphuric acid is slowly
added to water? What type of change is it?
Answer: When sulphuric acid is slowly added to water, the solution will become hot. This is a physical process. Here, two liquids are just mixed, and no new substances are produced.

Question 4. Complete the table
Answer:

Question 5. Write four differences between a physical change and a chemical change.
Answer: See Table 2.6.

Question 6. What do you mean by periodic and non-periodic changes? Give example.
Answer: The changes which occur again and again after a fixed interval of time are called periodic changes.

The changes which do not take place after a regular or fixed interval of time are called non-periodic changes.

To and fro movement of a pendulum is an example of a periodic process. The movement of a car along a straight road is an example of a non-periodic process.

WBBSE Class 6 Science Question Answer

Question 7. Classify the following as chemical or physical change: plants preparing their own food; taking X-ray photographs of a broken bone; dissolving chlorine in water; melting of wax; ripening of fruit.
Answer: Plants preparing their own food: Chemical change;
Taking X-ray photograph of a broken bone: Chemical change;
Dissolving chlorine in water: Physical change; Melting of wax: Physical change;
Ripening of fruit: Chemical change.

Question 8. Chemical fertilizers and insecticides may cause harm to nature. Why then should we use them?
Answer: Chemical fertilizers and insecticides are harmful to nature when they are used in excessive amounts.

When they are used in a recommended amount and all the guidelines are followed regarding their usage, they increase the productivity of the crops without causing pollution and health effects.

It helps to destroy the insects causing damage to crops in a short time. So farmers don’t have to depend on natural processes.

Hence the production of large amounts of food grains is possible to meet the growing demand for food worldwide.

Question 9. Give an example to justify that physical and chemical changes can occur simultaneously.
Answer: When a candle burns in the air, a part of the wax initially melts. This is only a change in the physical state of the matter.

When cooled, the molten part will again solidify. So it is a physical change. A major part of the candle (wax) is converted to carbon dioxide and water.

They are different substances. They are produced during the burning of the candle. So this is a chemical change.

Hence, when a candle burns both physical and chemical changes occur simultaneously.

Question 10. Write a short note on the chemical process.
Answer: The changes which involve the formation of one or more new substances having a completely different set of properties compared to the original substances are called chemical changes.

Rusting of iron, ripening of fruit, burning of a piece of paper etc. are all examples of chemical changes.

During these processes, in each case, new substances are formed. Chemical processes are usually irreversible.

Once the change occurs, it is not possible to get back the original substances. During a chemical change, either absorption or emission of heat must occur.

Question 11. When puffed rice (more) is prepared from rice, is it a physical or chemical change?
Answer: When puffed rice is prepared from rice, a chemical change occurs. New substances are formed during this and we cannot get back rice from the puffed rice.

Question 12. Rusting of iron is a chemical change. -Justify.
Answer: Rust is formed on the surface of iron when the iron surface is exposed to moist air for a prolonged time. It is a chemical process.

WBBSE Class 6 Science Question Answer

Rust is a new substance called hydrated iron oxide formed due to the interaction between pure iron, water and oxygen.

Question 13. Write the names of two substances which are added to water to kill the germs.
Answer: Chlorine and halogen tablet are often added to water to kill the germs.

Question 14. Illustrate with an example how the speed of a chemical process can be made faster.
Answer: A glass of clear limewater is taken. If it is kept in the open air for a few days, it turns milky.

This occurs because lime water reacts with the carbon dioxide gas present in the air and forms an insoluble, solid substance (known as calcium carbonate).

This solid, insoluble substance remains suspended within the solution. So, limewater turns milky. It is a chemical change but a slow change.

It is slow because the concentration of carbon dioxide in the air is very small.

So it requires time to produce a sufficient amount of that insoluble substance to turn the clear limewater milky.

But if we can increase the concentration of carbon dioxide we can speed up this reaction.

This can be done by blowing air through a piece of straw into the clear lime water.

Within a few minutes, the lime water turns milky. This occurs because the concentration of carbon dioxide is higher in the air that we breathe out.

So the chemical reaction occurs more quickly.

Question 15. Give examples of two irreversible physical changes.
Answer: Irreversible physical changes:

1. Glassware breaking into pieces
2. Making of flour from wheat

Question 16. When a magnesium ribbon is burnt in the air it forms a white powder. What type of change is this? What is the chemical name of the white powder?
Answer: The burning of magnesium ribbon in the air is an example of chemical change. When magnesium metal burns it reacts with oxygen found in air to form a white powder which is chemically known as magnesium oxide.

Question 17. Classify the following processes as desirable non- desirable and natural man-made processes: (1) Forest fire (2) explosion of the atomic bomb (3) tide and ebb (4) planned afforestation
Answer:

1. Forest fire: non-desirable natural process the explosion of the atomic bomb: non-desirable man-made process
2. Tide and ebb: desirable natural process planned afforestation: desirable man-made process

Question 18. Mention the names of a few factors which speed up the rate of a chemical change.
Answer: Factors that affect the rate of a chemical change include:

1. the concentration of reactants which participate in the chemical change
2. the surface area of reactants
3. temperature
4. physical states of the reactants presence of catalyst etc.

Chapter 1 Interdependence Of Organisms And Environment Review Questions MCQs

Question 1. In any community, various populations live

1. independently
2. dependently
3. defencelessly
4. interdependently

Answer: 4. interdependently

Question 2. An example of a stem tuber is

1. Potato
2. Onion
3. Ginger
4. Ol

Answer: 1. Potato

Read And Learn More: WBBSE Solutions For Class 6 School Science

Question 3. An example of a root tuber is

1. Potato
2. Quinine
3. Sweet potato
4. Beet

Answer: 2. Quinine

Question 4. The following constituent is used as roughage

1. Sucrose
2. Maltose
3. Cellulose
4. Starch

Answer: 3. Cellulose

Question 5. The flower(s) that is consumed include(s)

1. Cauliflower
2. Broccoli
3. Both
4. None

Answer: 3. Both

Class 6 Science Question Answer WBBSE

Question 6. Which of the following is obtained from animals?

1. Cotton
2. Wool
3. Hessian bag
4. Coins

Answer: 2. Wool

Question 7 _________is called the ‘sweeper bird.’

1. vulture
2. owl
3. crow
4. heron

Answer: 3. crow

Question 8. Which substance is not obtained from plants?

1. paper
2. gum
3. Quinine
4. curd

Answer: 4. curd

Question 9. Erythromycin is obtained from

1. bacteria
2. plants
3. animals
4. fungi

Answer: 1. bacteria

Question 10. Resin is commonly associated with

1. Gnetum
2. Banyan
3. Neem
4. Pinus

Answer: 2. Banyan

Question 11. The following alkaloid helps in the reduction of high blood pressure

1. Amarogentin
2. Reserpine
3. Quinine
4. Atropine

Answer: 2. Reserpine

Question 12. The process of photosynthesis utilizes

1. CO2
2. Water
3. Both
4. Oxygen

Answer: 3. Both

Class 6 Science Question Answer WBBSE

Question 13. Clownfish develop a symbiotic association with

1. Sea star
2. Sea anemone
3. Sea urchin
4. Hydra

Answer: 2. Sea anemone

Question 14. Cuscuta is a

1. Root parasite
2. Stem parasite
3. Leaf parasite
4. None of them

Answer: 3. Leaf parasite

Question 15. Ascariasis is the other name for an infection caused by

1. Pinworm
2. Tapeworm
3. Roundworm
4. Liver fluke

Answer: 2. Tapeworm

Question 16. An association between two individuals where both are benefitted is called

1. predation
2. competition
3. parasitism
4. symbiosis

Answer: 4. symbiosis

Question 17. The microbes present in curd is

1. Lactobacillus
2. Rhizobium
3. Streptomyces
4. Saccharomyces

Answer: 1. Lactobacillus

Class 6 Science Question Answer WBBSE Chapter 1 Interdependence Of Organisms And Environment Fill In The Blanks

Question 1. The edible stem of Amorphophallus is called __________
Answer: corm

Question 2. The edible part of celery is __________
Answer: petiole

Question 3. The largest plant fibre is __________
Answer: ramie

Question 4. Hemp comes from __________
Answer: Cannabis

Question 5. __________ is cultivated in cropland to increase nitrification.
Answer: Azolla

Question 6. Tannin comes from the stem of __________
Answer: Emblica

Question 7. The alkaloid used against malaria is __________
Answer: quinine

WBBSE Class 6 Science Question Answer

Question 8. The oxygen liberated in photosynthesis comes from __________
Answer: water

Question 9. Tapeworm from pork is also called __________
Answer: Taenia solium

Question 10. The red-coloured flower is mostly pollinated by __________
Answer: bird

Question 11. Aspergillus is a __________ parasite.
Answer: facultative

Question 12. Carrot has a high amount of __________
Answer: vitamin A

Question 13. Streptomycin is produced from __________
Answer: Streptomyces

Question 14. Curd production is brought about by __________
Answer: Lactobacillus

Question 15. A unicellular fungus causing fermentation is __________
Answer: yeast

Chapter 1 Interdependence Of Organisms And Environment Fill In The Blanks Identify As ‘True’ Or ‘False”

Question 1. Radish is an edible root.
Answer: True

Question 2. The most widely consumed grain in the world is wheat.
Answer: False

Question 3. Linen is made from the stem of Flax.
Answer: True

Question 4. The evolution of carbon dioxide during the production stage is responsible for the porous texture of the bread.
Answer: True

Class 6 Science Question Answer WBBSE

Question 5. Berry is a fleshy fruit.
Answer: True

Question 6. Ants and bees have a symbiotic association.
Answer: False

Question 7. Frog predates reptiles.
Answer: False

Question 8. Herons and Rhinoceros have a symbiotic association.
Answer: True

WBBSE Class 6 Science Question Answer

Question 9. Puccinia causes black stem rust of wheat.
Answer: True

Question 10. Mycobacterium causes the disease of TB.
Answer: True

Question 11. Scavenger hunt and kill animals for their consumption.
Answer: False

Question 12. Pigs act as a natural scavengers.
Answer: True

Question 13. Lactobacillus convert sucrose to lactic acid.
Answer: False

Question 14. Penicillium is a common mould.
Answer: True

Question 15. Streptomyces produces an antitubercular drug.
Answer: True

Class 6 WBBSE Science Question Answer Chapter 1 Interdependence Of Organisms And Environment Match The Columns

 

Answer: A-4,B-3,C-5,D-1

 

Answer: A-5,B-3,C-4,D-2

 

Answer: A-4,B-3,C-5,D-2

 

Answer: A-4,B-2,C-5,D-3

Chapter 1 Interdependence Of Organisms And Environment Answer In Words Or A Sentence

Question 1. Name the plant which produces fibre from leaves.
Answer: Agave sisalana leaf fibres are used to make rope.

Question 2. Name four underground modified stems.
Answer: Tuber of potato, bulb of onion, rhizome of ginger and corm of ol.

Question 3. What are the conditions for bat pollination?
Answer: The flower should be nocturnal and they are large in size.

Question 4. How are banyan seeds dispersed?
Answer: Since the banyan fruits are edible and red in colour, they are consumed by birds and afterwards, the seeds come out with their excreta in a different place.

Class 6 WBBSE Science Question Answer

Question 5. Which organs are damaged by malaria?
Answer: The organs affected by malaria are the liver and spleen apart from blood.

Question 6. What type of relation is exhibited by the Hermit crab and Sea anemone?
Answer: They exhibit symbiosis.

Question 7. How is tannin helpful for plants?
Answer: Tannin stored in the plant body protects them from fungal infection.

Question 8. How is latex useful to plants?
Answer: Latex comes out in the event of mechanical injury and protects the plant from secondary infection.

WBBSE Class 6 Science Question Answer

Question 9. Give two examples of medicinal plants.
Answer: Cinchona and Rauwolfia.

Question 10. How do animals act as scavengers?
Answer: Animals like crows, and pigs feed on different types of waste products and organic matter and clean the environment, and thus they are called natural scavengers.

Question 11. Name two birds which use holes in trees as their nests.
Answer: Woodpeckers and owls.

Question 12. Name the vitamins found in cod liver oil.
Answer: Vitamin A and Vitamin D.

Question 13. Name two animal fibres.
Answer: Wool and Silk.

Question 14. What is an antibiotic?
Answer: An antibiotic is a type of antimicrobial substance that inhibits the growth of or destroys microorganisms and combat bacterial infections.

Question 15. Name a marine natural scavenger.
Answer: White shark

Chapter 1 Interdependence Of Organisms And Environment Short Answer Type Questions

Question 1. What is the importance of ramie fibres?
Answer: Ramie fibres are long durable fibres which are woven to make light clothes that are not easily stained.

Question 2. What is the source and use of resin?
Answer: Resin is produced from the stem of the Pinus. It is used as a polishing agent and also as an organic solvent for paints.

Question 3. What are the features of insect-pollinated flowers?
Answer: The flowers have bright colour, pollen grains are sticky, petals provide a seat for the insects and they have nectaries.

Question 4. How alkaloids are important as medicines?
Answer: Alkaloids are useful against different diseases: quinine is useful to treat malaria, amelogenin is useful to treat Kalazar etc.

Class 6 WBBSE Science Question Answer

Question 5. What is streptomycin?
Answer: Streptomycin is an antibiotic produced by Streptomyces, which is useful against tuberculosis bacteria.

Question 6. Why is cotton cloth useful to treat an injury?
Answer: Cotton cloth gauze is formed of loosely woven threads. It is a very good absorbent and thus, useful to treat injury.

Question 7. What is silk fibre?
Answer: Silk fibre is a protein secretion from the silk gland of silkworms, which solidifies as a thread when they come in contact with air.

The colour and texture of the silk thread depend on the type of food consumed by the silkworm.

Question 8. What is meant by Taeniasis?
Answer: Taeniasis means tapeworm infection, which might occur due to the consumption of contaminated pork or beef.

Question 9. What is meant by a facultative parasite?
Answer: Facultative parasite normally survives in a decaying substance as a saprophyte, but may act as opportunistic parasite invading higher organism, e.g. Aspergillus.

Question 10. How do aphids and ants live together?
Answer: The aphid and ant follow a unique symbiotic relationship.

The aphids feed on plant sap and produce the excreta called honeydew, which is consumed by ants, while aphids remain well protected within the ant’s nest.

Question 11. Bread has many pores – explain why?
Answer: The dough made of wheat or flour is fermented by yeast to produce bread. Carbon dioxide and alcohol are also produced in this process.

Carbon dioxide helps in the swelling of the dough. Later mild heating causes the carbon dioxide to be liberated thereby causing the porous texture of the bread.

Question 12. What is the utility of vitamin A in our body?
Answer: Vitamin A is a potential source of retinol which helps in the synthesis of rod cells in the retina of the human eye that are responsible for low-light vision.

Question 13. Which organisms are called scavengers of nature and why? Are carnivores scavangers?
Answer: Scavengers are the organisms which consume dead and decaying remains of plants and animals that have either died of natural reasons or have been killed by another carnivore.

Ex. crow, vultures etc.

Almost none of the carnivores in the world are pure scavengers since carnivores (such as tigers) hunt and kill animals for their own consumption.

Question 14. Explain two roles of microbes in the production of medicines.
Answer: Microbes are useful sources of medicines like antibiotics.

Penicillin is produced from the green mould Penicillium notatum. Antibiotics like streptomycin and erythromycin are produced from streptomyces bacteria.

Question 15. How is curd prepared?
Answer: Curd is prepared by mixing lukewarm milk with a portion of curd prepared earlier. A bacteria called Lactobacillus lactis exists in the already-prepared curd.

Class 6 WBBSE Science Question Answer

This bacteria helps in the fermentation of the lactose sugar of milk to lactic acid.

After a few hours, some other changes take place in the milk and it is transformed into curd. The lactic acid formed prevents further growth of pathogenic bacteria in curd.