Question

Respiration is a chemical change because:
A. New substances are formed
B. Change in mass
C. Both a and b
D. Change is temporary.

Answer 1

Hint: We should know that respiration is a biochemical process in which cells of an organism obtain energy by oxidation and new substances like carbon dioxide and water are formed.

Complete step by step solution:
As we know respiration is a physiological combination of both physical and chemical changes in all organisms. In Fact, in simplest organisms like bacteria, they depend upon physical diffusion to supply oxygen to their respiratory machinery.
Three types of respiration are there:
External respiration- In this respiration, breathing process is involved i.e, inhalation and exhalation of gases.
Internal respiration- This type of respiration involves exchange of gases between blood and body cells.
Cellular respiration- In this respiration, several metabolic processes take place i.e. converting energy stored in biological molecules to usable energy in the form of ATP. Only in this respiration chemical changes takes place.
Respiration is a chemical process in which organic compounds breakdown and release energy. The compounds change into different ones by several exothermic reactions.
The overall chemical equation for cellular respiration is given below:
${ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ O }_{ 2 }\longrightarrow { 6C }{ O }_{ 2 }+{ 6H }_{ 2 }O+36ATP$
On inspecting the above reaction, we can easily say that new substances like carbon dioxide and water are formed. Also, in the above reaction there is change in mass as glucose is oxidized by oxygen and heat energy is released.
Hence, option C is the correct answer.

Note: One should remember the following reaction of cellular respiration:
The energy released in cellular respiration is stored in the form of ATP.
The cellular aerobic respiration partially occurs in cytoplasm and partially in the mitochondria.
On breakdown of 1 molecule of glucose, 36 ATPs are produced.
During cellular respiration, change in mass occurs due to oxidation of glucose.