Question

Which component of the inhaled air is used by the body?
(a) Carbon dioxide
(b) Nitrogen
(c) Oxygen
(d) Hydrogen

Answer 1

Breathing (or ventilation) is the process of moving air out of and into the lungs to allow for gas exchange with the internal environment, primarily to flush out carbon dioxide and bring in oxygen. All aerobic creatures require oxygen for cellular respiration, which breaks down food for energy and produces carbon dioxide as a waste product.

Complete answer:
Breathing, also known as "external respiration," transports air into the lungs, where gas exchange occurs via diffusion in the alveoli. The circulatory system of the body transports these gases to and from the cells, where "cellular respiration" takes place.
The air we breathe in and out is not entirely composed of pure oxygen or carbon dioxide. As we all know, our bodies and cells require more oxygen to respire and perform their normal functions, and our environment does not provide us with an unlimited supply of oxygen. In the same way, when we breathe out, we only expel carbon dioxide.
The air we breathe in contains 21% oxygen and 0.04 percent carbon dioxide, whereas the air we breathe out contains 16.4 percent oxygen and 4.4 percent carbon dioxide. This is because our cells release energy by using oxygen from inhaled air and emit carbon dioxide as a byproduct.
All vertebrates with lungs breathe in and out through a highly branched system of tubes or airways that lead from the nose to the alveoli. The breathing rate, or the number of respiratory cycles per minute, is one of the four primary vital signs of life.
Thus, Respiration includes inhalation (breathing in) and exhalation (breathing out). During inhalation, oxygen is inhaled along with air, which is a key component in metabolism.

As a result, the correct option is Option C: 'Oxygen.'

Note: We all are aware that our atmosphere is a mixture of gases and it contains 78 % nitrogen, 21% oxygen, 1% argon, 0.04 % carbon dioxide, 0.5 % water vapor. When we breathe in, we inhale the same mixture of gases contained in the atmosphere as our nose cannot filter out the oxygen from other gases.