WBBSE Class 8 School Science Chapter 4 Occurrence Of Carbon And Its Compounds In Nature VSAQs

WBBSE Chapter 4 Occurrence Of Carbon And Its Compounds In Nature VSAQs

Question 1. Which element is regarded as the building block of life?
Answer:

Carbon is regarded as the building block of life.

Question 2. What is the valency of carbon?
Answer:

Valency Of Carbon:

The valency of carbon is 4.

Question 3. What do you mean by allotropy?
Answer:

Allotropy:

The phenomenon in which some elements like carbon, sulfur, etc. exist in more than one form generally having the same chemical properties but some different physical properties in the same physical state is known as allotropy.

WBBSE Class 8 Very Short Answer Questions Carbon

Question 4. What do you mean by allotropes?
Answer:

Allotropes:

The different forms of an element having the same chemical properties but with different physical properties are called allotropes.

Question 5. Name two allotropes of sulfur.
Answer:

Allotropes Of Sulfur:

Two allotropes of sulfur are rhombic sulfur and monoclinic sulfur.

Read And Learn More WBBSE Solutions For Class 8 School Science Very Short Answer Type Questions

Question 6. Name two allotropes of phosphorous.
Answer:

Allotropes of phosphorous:

Two allotropes of phosphorous are red phosphorous and white phosphorous.

Question 7. Name three crystalline allotropes of carbon.
Answer:

Crystalline allotropes of carbon:

Three crystalline allotropes of carbon are diamond, graphite, and fullerene.

Question 8. Name three amorphous allotropes of carbon.
Answer:

Amorphous allotropes of carbon:

Three amorphous allotropes of carbon are coke, charcoal, and gas carbon.

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Question 9. Name the purest form of charcoal.
Answer:

Purest form of charcoal:

Destructive distillation of sugar forms sugar charcoal and it is the purest form of charcoal.

⇒ \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} \stackrel{\mathrm{H}_2 \mathrm{SO}_4}{\longrightarrow} 12 \mathrm{C}+11 \mathrm{H}_2 \mathrm{O}\)

Question 10. What do you mean by the heating value or the calorific value of a fuel?
Answer:

Heating value or the calorific value of a fuel:

The amount of heat generated on complete combustion of 1-kilogram fuel in presence of oxygen is called the heating value or calorific value of that particular fuel.

Question 11. What is the unit of heating value or calorific value of a fuel?
Answer:

Unit of heating value or calorific value of a fuel:

The heating value or calorific value of a fuel is generally expressed in units of kilocalorie per kg. or kilo Joule per kg.

Question 12. Which is the main constituent of CNG?
Answer:

Main constituent of CNG:

Methane is the main constituent of CNG.

Question 13. Name two alternative sources of energy.
Answer:

Alternative sources of energy:

Solar energy and wind energy are two alternative sources of energy.

Question 14. Name two carbon-containing metallic ore.
Answer:

Carbon-containing metallic ore:

Calcium carbonate and magnesium carbonate are two carbon-containing metallic ores.

Very Short Answer Format Class 8 Science

Question 15. Which of the allotropes of carbon is a good conductor of both heat and electricity?
Answer:

Graphite, one of the allotropes of carbon, is a good conductor of both heat and electricity.

Question 16. Arrange the following fuels in ascending order in terms of their calorific values: wood, LPG, coal
Answer:

In terms of calorific value, the order is wood < coal < LPG.

Question 17. Which of the allotropes of carbon are good conductors of electricity?
Answer:

Graphite (crystalline allotrope) and gas carbon (amorphous allotrope) are good conductors of electricity.

Question 18. What is the full form of CNG and LPG?
Answer:

Full form of CNG and LPG:

The full form of CNG is compressed natural gas and the full form of LPG is liquefied petroleum gas.

Question 19. Name one biodegradable and one non-biodegradable polymer.
Answer:

One biodegradable polymer is cellulose and one non-biodegradable polymer is polyvinyl chloride (PVC).

Question 20. Name three greenhouse gases. 
Answer:

Greenhouse Gases:

Three greenhouse gases are carbon dioxide, methane, and nitrous oxide.

WBBSE Chapter 4 Carbon Compounds Quick Answers

Question 21. Which is used as rocket fuel?
Answer:

Liquid hydrogen is used as rocket fuel.

Question 22. What is the main constituent of LPG?
Answer:

Main constituent of LPG:

Butane is the main constituent of LPG.

Question 23. What do you mean by biodegradable polymer?
Answer:

Biodegradable Polymer:

Biodegradable polymer is a class of polymer compounds that undergoes degradation by living organisms such as microbes, bacteria, fungi, etc. Examples: cellulose, jute, etc.

Question 24. Which gases are emitted from the combustion of fossil fuels?
Answer:

Burning of fossil fuels produces oxides of carbon, nitrogen, sulfur, etc besides water.

Question 25. How does the percentage of fixed carbon affect the calorific value of coal?
Answer:

The higher the value of fixed carbon, the greater the calorific value of coal.

Question 26. Mention the names of some fuels obtained from biomass.
Answer:

Fuels from biomass-

1. Solid fuel: charcoal, logs
2. Liquid fuel: tar, vegetable oil
3. Gaseous fuel: biogas.

Question 27. What is the shape of a diamond crystal?
Answer:

Octahedral (or cubic) crystal.

Class 8 Science Occurrence of Carbon Study Guide

Question 28. What is activated or active charcoal?
Answer:

Activated or Active Charcoal:

Charcoal, with high power of adsorption and high decolorizing properties along with certain catalytic power, is known as activated or active charcoal.

Question 29. When clear lime water in a vessel is exposed to air, a white scum is seen to float on the surface after some time: Why?
Answer:

Aerial carbon dioxide forms insoluble calcium carbonate by superficial contact with clear lime water and the insoluble calcium carbonate floats on the surface as scum.

Question 30. CO₂ is not collected by the downward displacement of cold water but can be collected by the downward displacement of hot water.
Answer:

CO₂ dissolves in water but the solubility decreases with the rise of temperature. Hence the gas may be collected by the downward displacement of hot water.

Very Short Answer Questions for Carbon Compounds

Question 31. Name an absorbent of CO₂.
Answer:

Absorbent of CO₂

CO₂ is absorbed by caustic potash (KOH) solution.

⇒ \(2 \mathrm{KHO}+\mathrm{CO}_2=\mathrm{K}_2 \mathrm{CO}_3+\mathrm{H}_2 \mathrm{O}\)

Question 32. Find the odd one out Carbon, sulfur, phosphorus, Sodium
Answer:

Sodium: Does not show allotropy.