AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
(B) Change in shape
The textbook lists change in state, change in colour, evolution of a gas, and change in temperature as indicators of a chemical reaction — not change in shape.
Source: Chemical Reactions and Equations, Chapter 1 (Activity 1.1–1.3)
The four recognised indicators of a chemical reaction (from the NCERT text) are: change in state, change in colour, evolution of a gas, and change in temperature. "Change in shape" is a physical change (e.g., cutting, moulding) and does not indicate a new substance has formed. Examiners expect you to recall this list exactly.