Question

As we go higher into the atmosphere, the air becomes _____.
A) Thinner
B) Denser
C) Warmer
D) Visible

Answer 1

Hint: Atmosphere refers to the layers of gases that envelope a planet or a heavenly body. On a given planet or a heavenly body, the atmosphere will only be able to exist when the gravitational force of the planet is high and the surface temperature of that planet is low.

Complete answer:
The atmosphere of a planet is held around the planet by the gravitational force of the planet itself. Another condition that supports the existence of the atmosphere is low temperature. When the temperature of the planet increases, the air becomes rare and light. Hence, this lighter or thinner air moves upwards, i.e. away from the surface of the planet. Therefore, as the altitude increases, the air becomes thinner or rarer or lighter.

Another reason for this same phenomenon is the gravitational force of the planet. The planet’s gravitational force is the highest on its surface. As we move above or below, the force decreases. Therefore, at a significant height in the atmosphere, the gravitational force is very less. In this region, only light and thin air exist. If the air is to get dense, it would automatically get pulled down towards the surface of the planet and the region at the given height will still experience the presence of this air.

Thus, the correct answer is Option (A), As we go higher into the atmosphere, the air becomes thinner.

Note: The earth’s atmosphere consists of 78% nitrogen, 21% oxygen, approximately 1% argon and less than even 1% are the remaining gases. The atmospheres of the gas giants in our solar system, i.e. Jupiter, Saturn, Uranus and Neptune are all made up of 85% hydrogen and 10 to 20% Helium. Mercury has 42% oxygen in its atmosphere, while Venus and Mars have more than 90% of carbon dioxide in theirs.