Which of the following is not a chemical reaction ?

Correct option is D

The correct answer is (d) Conversion of water into steam.
 The conversion of water into steam is a physical change, not a chemical reaction.
 In this process, water changes its state from liquid to gas (steam) due to heating, but its chemical composition (H2O) remains unchanged.
 Physical changes involve changes in the state or appearance of a substance without altering its chemical identity.
 Unlike chemical reactions, physical changes are usually reversible, such as water vapor condensing back into liquid water.
Important Key Points:
 Conversion of water to steam is a physical change.
 Chemical composition of water remains H2O.
 Physical changes are usually reversible.
 No new substances are formed in physical changes.
 Examples include melting, freezing, and boiling.
 Chemical reactions involve the formation of new substances.
Knowledge Booster:
 Burning of coal: This is a chemical reaction where coal (carbon) reacts with oxygen to produce carbon dioxide and other compounds, releasing energy.
 Digestion of food: A complex chemical reaction where enzymes break down food into nutrients that can be absorbed by the body.
 Burning of paper: A chemical reaction where paper combusts in the presence of oxygen, producing carbon dioxide, water vapor, and ash.