Question

A. MCQ-Choose the correct answers.
1. Which gas do mountaineers carry in their cylinders
(a) nitrogen
(c) carbon dioxide
b) oxygen
(d) none of these
2. Air is used for
(a) separating husk from grains
(b) flying by birds
(c) dispersal of seeds
(d) all of these
3. The oxygen present in the air is used for
(a) respiration
(b) extinguishing fire
(c) burning
(d) both (i) and (m)
4. The percentage of which gas found in air is incorrect?
(a) oxygen-21%
(c) noble gases-0.95%
5. Which two main processes maintain the balance of carbon dioxide and oxygen in the
atmosphere?
(a) photosynthesis and burning
(c) respiration and photosynthesis
(b) nitrogen-87
(d) carbon dioxide0.03%
(a) oxygen
(b) buming and respiration
(d) none of these
6. Which gas present in air is used by plants for making food through photosynthesis
(b) carbon dioxide
(c) nitrogen
(d) noble gases
7. Which
gas is released by green plants during the process of making their food?
(a) oxygen
(b) carbon dioxide
(d) noble gases
(c) nitrogen
8. Which gas(es) present in the air does not support burning
b) nitrogen
(a) oxygen
c) carbon dioxide
(d) nitrogen and carbon dioxide​

Answer 1

Answer:

1. b) oxygen

2. d)all of these

3. d) both a and c

4. b) nitrogen 87%

5. c) respiration and photosynthesis

6. b) carbon dioxide

7. a) oxygen

8. d) nitrogen and carbon dioxide