Question

Pure air contains nitrogen, oxygen and small amounts of other gases. The noble gases have been left out of the table. Which row shows the composition of dry, unpolluted air?
A.Nitrogen-$21\% $, oxygen-$78\% $, other gases- small amount of carbon dioxide
B.Nitrogen-$21\% $, oxygen-$78\% $, other gases- small amount of carbon monoxide
C.Nitrogen-$78\% $, oxygen-$21\% $, other gases- small amount of carbon dioxide
D.Nitrogen-$78\% $, oxygen-$21\% $, other gases- small amount of carbon monoxide

Answer 1

Hint:To answer this question, you should recall the composition of air around us. We all know that air surrounds us everywhere on this planet. One cannot imagine the existence of life without air. The composition of air is not constant and changes from place to place. Nitrogen is present in large amounts in our atmosphere with traces of carbon dioxide.

Complete step by step answer:
We know that water present in oceans and rivers evaporates during summer and escapes into the air. Thus, water vapor is one of the components of the air. It occupies very less percentage of earth’s atmosphere. The composition of air is: Oxygen: Air contains some matter which supports combustion. This substance is oxygen.

Air comprises almost $21\% $ oxygen. Nitrogen: When you blow over a burning candle you notice that it extinguishes. This means air contains incombustible gases. Nitrogen occupies nearly $78\% $ of earth’s atmosphere and is the most abundant gas on our planet. Carbon dioxide: Carbon dioxide is mainly produced due to respiration by plants and animals or burning of fuel. It occupies \[0.038\% \]of the earth’s atmosphere.

Hence, the correct answer to this question is option C.

Note:
You should know that while air is mostly gas, it also holds lots of tiny particles. These particles in the air are called aerosols. Some aerosols—like dust and pollen—are picked up naturally when the wind blows. But the air can also carry particles that cause air pollution, such as the soot, smoke and other pollutants from car exhaust and power plants. When there are too many particles in the air, it can be difficult for plants and animals to breathe.