Question

Exercises
T'S UNDERSTAND
Objective type questions
1. Choose the correct option.
1. Air is made up of
(a) one gas (b) three gases (c) several gases (d) none of t
2. Gas with the highest percentage in air is
(a) oxygen (b) nitrogen (c) carbon dioxide (d) water vapour
3. Air contains
(a) oxygen (b) water vapour (c) dust and smoke (d) all of these
4. For photosynthesis, plants need
(a) nitrogen (b) oxygen (c) carbon dioxide (d) none of these
5. Main causes of air pollution are
(a) excessive burning of fuels (b) burning of wood
(c) vehicles releasing smoke (d) all of these

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Answer 1

Answer:

1. (c) several gases

2.(b) nitrogen

3.(d) all of these

4.(c) carbon dioxide

5.(d) all of these

Answer 2

Explanation:

1) C) Several Gases - air is a mixture of different type of gases for e.g. Nitrogen, Oxygen , Carbon dioxide , Argon ,Water vapours etc.

2) B) Nitrogen - Nitrogen is contributing 78.09%.

3) D) All of these - air contains Oxygen , Nitrogen , Water vapours or dust and smoke also.

4) C) For photosynthesis plants need Carbon Dioxide.

5) D) All of these - excessive burning of fuels , wood & vehicle releasing smoke all will cause air pollution and these are pollutants.