Important Questions Test: Air Around Us - UPSC MCQ

Humidity refers to the amount of water vapor present in the air.

The finer hairs inside the nose, known as cilia, help filter out dust particles and other small debris from the air we inhale. This prevents them from entering the lungs.

Winnowing is used to separate grains from husk due to difference in their density.

The layer of air surrounding the Earth's surface is called the atmosphere. It consists of several layers, including:

• Troposphere
• Stratosphere

The atmosphere plays a crucial role in supporting life by:

• Providing oxygen
• Protecting the planet from harmful solar radiation

The density of air decreases with height as we move upwards because atmospheric pressure diminishes at higher altitudes, leading to lower air density. Additionally, temperature typically decreases with altitude in the troposphere, contributing further to the reduction in air density.

• Density of air decreases with height.
• Atmospheric pressure diminishes at higher altitudes.
• This reduction in pressure leads to lower air density.
• Temperature typically decreases with altitude in the troposphere.
• The decrease in temperature further contributes to the reduction in air density.

Gases and dust particle together make the smoke. Smoke starts from burning substances.

Atmospheric pressure decreases with height because:

• As you go higher, the layer of atmosphere above becomes thinner.
• This reduction in air density occurs due to gravity pulling air molecules closer to Earth.
• As a result, there is lower atmospheric pressure at greater heights.

The glass which is empty is actually filled with air. And because air takes up space when an empty glass is inverted and inserted into a trough filled with water, the air is trapped within and it is no anyway for air to escape out.

The balance between carbon dioxide and oxygen is maintained by photosynthesis and respiration in which carbon dioxide and oxygen is used and oxygen and carbon dioxide is produced respectively.

Nitrogen gas is found in the largest quantity in air, making up approximately 78% of Earth's atmosphere. This is followed by oxygen at around 21%.