Q1. Which of the following statements is incorrect for a chemical change?
A A gas may be evolved.
B Heat may be produced but never absorbed. Correct
C Sound may be produced.
D A colour change may take place.
Explanation
Heat may be produced but never absorbed is the incorrect statement because chemical changes can be exothermic or endothermic. Burning releases heat, while processes such as thermal decomposition may absorb heat. Gas evolution is a common sign of a chemical reaction, as seen when acids react with carbonates. Sound may also be produced in some reactions, especially rapid or explosive ones. A colour change can occur when new substances with different properties are formed.