The blanket of air surrounding the earth is known as the:

1. Ozone layer
2. Nitrogen layer
3. Lithosphere
4. Atmosphere

What is A% and B% as depicted in the diagram showing the composition of the atmosphere

1. A: 72 B: 27
2. A: 77 B: 22
3. A: 78 B: 21
4. A: 79 B: 20

Name the densest layer of the atmosphere.

1. Exosphere
2. Troposphere
3. Stratosphere
4. Mesosphere

Mountain climbers set up camps at the base as well as at regular intervals along their climb. Why?

1. To acclimatize their bodies to lower concentration of air.
2. To acclimatize their bodies to lower temperature.
3. To acclimatize their bodies to pressure.
4. All of the above.