1.) What is a catalyst?

2.) What is hydrogenation?

3.) What is the valency and atomic weight of oxygen?

4.) What is nascent oxygen?

5.) What is chemical nitrogen?

6.) What percent of nitrogen contribute to form air?

7.) What is ozone? Write its formula.

8.) Define: i) global warming ii) ozonosphere iii) ODS

9.) Which chemical is used to react with NH Cl to produce nitrogen gas in the laboratory?

10.) Write the composition of air with the help of a pie chart.

11.) Give any four precautions to be taken during the laboratory preparation of hydrogen gas.

12.) How do you test hydrogen gas?

13.) Write any three physical properties and three uses of hydrogen gas.

14.) What property of hydrogen enables it to be collected by downward displacement of water in a gas jar?

15.) What is the role of manganese dioxide in the preparation of oxygen gas in the laboratory?

16.) Enlist the physical properties of oxygen. Write any three uses of it.

17.) What happens when burning charcoal is kept in a gas jar containing oxygen?

18.) A burning candle, when brought near the mouth of a gas jar containing hydrogen, starts with a pop sound but it is extinguished when inserted inside the jar. Why?

19.) How do you test the oxygen gas in a jar? Explain any one method in brief.

20.) Give any three precautions which should be noted for the preparation of nitrogen in the laboratory.

21.) What are the physical properties of nitrogen?

22.) What happens when a burning magnesium ribbon is inserted in a jar containing nitrogen gas? Also write the chemical equation.

23.) What are the uses of nitrogen?

24.) What is ozone? How is it formed in the atmosphere?

25.) The main causes of ozone layer depletion are the activities of human beings. Clarify this statement.

26.) What are the causes of the ozone layer depletion? How do CFCs deplete the ozone? Explain with chemical equations.

27.) Suggest any four ways to conserve the ozone layer in the stratosphere. How do we know about the large amount of UV rays reaching a certain part of the earth? Explain.

28.) Write the importance of the ozone layer for the existence of life on the earth.

29.) Concentrated H,SO, cannot be used instead of dilute H,SO, in the laboratory preparation of hydrogen gas. Why?

30.) Hydrogen gas is collected by downward displacement of water. Why?

31.) Pure zinc is not used in the laboratory preparation of hydrogen gas. Why?

32.) Pure hydrogen gas is not used in balloons. Why?

33.) Oxygen is used by living organisms for respiration. Why?

34.) The mouth of a hard glass test tube is slightly slanted during preparation of oxygen gas. Why?

35.) Hydrogen and oxygen can be collected by electrolysis of water. Why?

36.) Ozone forms a protective layer around the earth's atmosphere. Why?

37.) Ozone causes different genetic diseases and cataract in humans. Why?

38.) Nitrogen gas is filled in an electric bulb. Why?

39.) Nitrogen gas is collected by downward displacement of water. Why?

40.) What happens when lead oxide reacts with hydrogen?

41.) What happens when potassium reacts with hydrogen?

42.) What happens when sodium reacts with oxygen?

43.) What happens when hydrogen burns with oxygen?

44.) What happens when ethane burns in oxygen?

45.) What happens when ethyl alcohol burns in oxygen?

46.) Write down the composition of air.

47.) Why is hydrogen called simplest element?

48.) Who discovered hydrogen gas? Write any-4 physical properties of Hydrogen.

49.) What is nascent Hydrogen?

50.) What is heavy hydrogen (Deuterium)?

51.) Zinc is mostly used for the laboratory preparation of hydrogen gas rather than other metals, why?

52.) Metals displace the hydrogen from acids, why?

53.) Hydrogen gas is not found in air why?

54.) Why is hydrogen used as a reducing agent?

55.) List any four uses of Hydrogen.

56.) How is hydrogen gas tested in lab?

57.) What happens when conc. H2SO4 is used during laboratory preparation of hydrogen gas?

58.) What reaction takes place when hydrogen is passed to red hot copper?

59.) How could it be known that hydrogen does not help other substances to burn?

60.) Who discovered oxygen gas? Why is oxygen important for living organisms?

61.) Write any four physical properties of oxygen.

62.) Write any five uses of oxygen gas.

63.) How do the aquatic animals get oxygen to respire?

64.) What happens when an alkaline pyrogallol solution is added to oxygen containing jar?

65.) Why is oxygen necessary for welding?

66.) What happens when carbon is burnt in the presence of oxygen? How would you prepare an acid from it? Explain with an equation?

67.) What happens when magnesium ribbon is burnt in air? How would you prepare an alkali from it? Explain with a chemical equation.

68.) What is the percentage (by volume) of oxygen gas in air? Why is oxygen regarded as an important gas?

69.) What is the percentage of Nitrogen in air? What is its advantage for us?

70.) Who discovered nitrogen gas?

71.) Nitrogen gas is an inactive gas. Why?

72.) Why the Nitrogen gas is collected in the gas jar by the downward displacement of water?

73.) Nitrogen gas is used for replacing fuels in fuel tanks of airplanes. Why?

74.) Write any five physical properties of Nitrogen gas.

75.) Write any five uses of Nitrogen gas?

76.) Why electric bulb is filled with nitrogen gas?

77.) Under what conditions nitrogen and hydrogen combine to form ammonia?

78.) Describe how the nitrogen gas is extracted from the air.

79.) Give a sure test for nitrogen.