Question

Which among the following is not a physical change?
(A) Melting of solids to liquids
(B) Vaporization of liquids to gases
(C) Liquefaction of gases to liquids
(D) Decay of matter

Answer 1

Hint: There is a large variety of chemical reactions that take place around us. The various types of chemical reactions and the following observations are useful to determine whether a chemical reaction has taken place as a change in physical state, change in color, evaluation of gas, and temperature change.


Complete step by step solution:
Physical change: Physical change is limited to a change that makes a difference in the display without changing the composition. It is defined as the change in shape and size of substance and there is no change in chemical composition, which results in no new substance will form. This change is only a physical and a reversible reaction.
(A) Melting of solids to liquids: it is a physical change because there is a change in physical state from solid to liquid. For example, the melting of ice given water.
(B) Vaporization of liquids to gases: it is a physical change because there is a change in physical state from liquid to gas. For example, boiling water to give water vapor.
(C) Liquefaction of gases to liquids: it is a physical change because there is a change in physical state from gas to liquid. For example, condensation of gases to liquids.
(D) Decay matter: it is a chemical change because it was not able to convert back to the initial substance, which means this is an irreversible process.


Hence, decay matter is not a physical change. So, option D is the correct answer.


Note: A chemical change is defined as the change in which the change occurs in the chemical composition and resulting in the formation of new compounds or substances. This process is not a reversible reaction. For example, decaying matter, combustion reactions, chemical battery usage, etc.