Question

Air is a mixture of various gases. One of the gases is 21% 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

The correct option is B

Oxygen

The correct option is B.

Explanation of correct option:

1. Most living things need oxygen to survive.
2. It is essential for organisms to grow, reproduce, and turn food into energy.
3. Humans get the oxygen they need by breathing through their noses and mouth.
4. Oxygen helps the cells break down food to produce energy for survival.

Explanation of incorrect options:

Option A:

1. Nitrogen makes up 78% of the air around us.
2. It is, however, not essential for the survival of human beings.

Option C:

1. The ozone layer makes up less than 1% of the earth's atmosphere.
2. It absorbs UV radiation and is thinning day by day.

Option D:

1. Argon makes up 0.9% of the earth's atmosphere.
2. It is not important for survival of human beings.

Final answer: The gas that is essential for the survival of humans is oxygen.