Question

Air is a mixture of various gases. One of the gases is 21% part of the air and is essential for the survival of human beings. This gas is :
A. Nitrogen
B. Oxygen
C. Ozone
D. Argon

Answer 1

Hint: The air around us is a mixture of gases, mainly nitrogen and oxygen, air also contains very smaller amounts of water vapor, argon, and carbon dioxide, and very small amounts of other gases, suspended dust, spores, and bacteria.
Complete step by step solution:
Earth's atmosphere is made of air. Air is a mixture of gases, 78% nitrogen and 21% oxygen with traces of water vapor, carbon dioxide, argon, and various other components.

So, the correct answer is option B.

Additional information:
Why is air important?
Air contains oxygen, which is essential for the survival of human beings.
Air supports burning or combustion.
Nitrogen present in air is essential for the growth of plants.
The ozone layer of ozone gas is present in the atmosphere, which protects us from the harmful ultraviolet radiation of the sun light.
Carbon dioxide is taken from the air by plants for photosynthesis and they release oxygen, by this way air is maintaining nature’s balance.

Note: A safe breathing gas for hyperbaric use has three essential features:
- It must contain sufficient oxygen to support life, consciousness and work rate of the breather.
- It must not contain harmful contaminants. Carbon monoxide and carbon dioxide are common poisons which may contaminate breathing gases. There are many other possibilities.
- It must not become toxic when being breathed at high pressure such as when underwater. - - Oxygen and nitrogen are examples of gases that become toxic under pressure.