The incorrect statement is (a) “Heat may be given out but never absorbed” because chemical reactions can both release and absorb heat depending on the specific reaction.
Explanation:
Exothermic reactions: These reactions release heat to their surroundings.
Endothermic reactions: These reactions absorb heat from their surroundings.
Why the other options are correct:
(b) Sound may be produced:
Some chemical reactions can produce sound, like the fizz of a firework or the crackling of burning wood.
(c) A color change may take place:
Color changes are a common indicator of a chemical reaction, as the change in molecular structure can affect the wavelengths of light absorbed and reflected.
(d) A gas may be evolved:
Many chemical reactions involve the production of a gas as a product, like the bubbling in baking soda and vinegar.