WBBSE Solutions For Class 8 School Science Chapter 3 Some Common Gases Very Short Answer Type Questions

Chapter 3 Some Common Gases VSAQs

Question 1. According to scientists, when the earth was created?
Answer:

According to scientists, the earth was created about 4500 million years ago.

Question 2. According to scientists, when life emerged on earth?
Answer:

According to scientists, life emerged on earth about 3500 million years ago.

Question 3. Which instrument is used in the laboratory to measure the temperature of an object? The thermometer is used in the Answer: laboratory to measure the temperature of an object.

Question 4. Where can you find cyanobacteria?
Answer:

Cyanobacteria can be found in wetlands, ponds and paddy fields.

Question 5. Name the polymer with which the copper wire is enveloped.
Answer:

Copper wire is enveloped by a polymer named PVC (polyvinyl chloride).

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Question 6. What do you mean by obligate anaerobes?
Answer:

Obligate Anaerobes:

There are some bacteria which live in the depth of marshes or sludge in urban sewers. Here oxygen is not at all available. These bacteria can survive without oxygen and die in presence of oxygen. Such organisms are called obligate anaerobes.

Question 7. What is carbogen?
Answer:

Carbogen:

Carbogen is a mixture of 95% oxygen and 5% COr Inhalation of carbogen is prescribed for patients who are rendered unconscious due to inhalation of a

Question 8. What are the three naturally occurring isotopes of oxygen?
Answer:

Oxygen has three naturally occurring isotopes, 16eO, ”0 and. (But the natural abundance of the last two is very low).

Question 9. Which gas of air is depleted due to combustion?
Answer:

Oxygen.

Question 10. Name a binary compound of oxygen which is not an oxide.
Answer:

FzO (fluoride of oxygen)

Question 11. What is an oxide?
Answer:

Oxide:

Actually oxide is a compound of two elements, one of which is oxygen.

Question 12. Give three examples of acidic oxide.
Answer:

Examples of acidic oxide:

Carbon dioxide (CO₂), sulphur dioxide (SO₂) and phosphorous pentoxide (P₂0₅) are examples of three acidic oxides.

Question 13. Name two amphoteric oxides.
Answer:

Aluminium oxide (Al203) and zinc oxide (ZnO) are two amphoteric oxides.

Question 14. Name one non-metallic peroxide and one metallic peroxide.
Answer:

Hydrogen peroxide (H₂O₂) is a non-metallic peroxide and sodium peroxide (Na₂O₂) is a metallic peroxide.

Question 15. Name a few metals which can adsorb oxygen.
Answer:

At normal or low pressure, certain metals like gold (Au), silver (Ag), platinum (Pt) and palladium (Pd) absorb oxygen.

Question 16. Which is the lightest element?
Answer:

Hydrogen is the lightest element.

Question 17. What are the melting point and boiling point of hydrogen?
Answer:

The melting point of hydrogen is – 259.2 °C and the boiling point of hydrogen is – 252.6°C.

Question 18. What are the three isotopes of hydrogen?
Answer:

Isotopes of hydrogen:

Hydrogen has three isotopes: and (The natural abundance of the last two is negligibly small)

Question 19. Name a few metals which can adsorb hydrogen at normal temperature.
Answer:

Some metals like palladium (Pd), platinum (Pt), iron (Fe), nickel (Ni), etc. can adsorb hydrogen at normal temperature

Question 20. What do you mean by “hydride”?
Answer:

Hydride:

Binary compounds of elements with hydrogen are called hydrides.

Question 21. Name one oxide compound which can be heated to produce hydrogen.
Answer:

Mercuric oxide (HgO), when heated, produces hydrogen.

Question 22. Name one compound which can be heated to produce oxygen.
Answer:

Oxygen is obtained from hydrogen peroxide (H₂O₂) at normal temperature.

Question 23. Name one metallic hydride compound.
Answer:

Lithium hydride (LiH)is an example of a metallic hydride compound.

Question 24. Which of the two gases hydrogen and oxygen is soluble in water
Answer:

Oxygen.