Question

Which of the following are natural chemical changes?

• A. Respiration
• B. Photosynthesis
• C. Explosion of fire works
• D. Combustion of fuels

Answer 1

Answer: (A), (B)

The correct options are
A Respiration
B Photosynthesis

Chemical changes are those which include formation of a new substance with different chemical properties.

Respiration is a natural process in which we inhale air and exhale carbon dioxide. In photosynthesis, green plants naturally convert light energy into chemical energy. Thus, new substances are being formed in both the cases.

In the process of explosion of fire work, heat energy is added manually. During combustion process, fuel is burnt by human beings in the presence of oxygen to form carbon dioxide and water. Thus, both of these are man-made chemical changes.