Question

Which of these given options is not an observation that indicates a chemical change?

• A. Evolution of a gas
• B. Change in temperature
• C. Formation of a precipitate
• D. Change in mass

Answer 1

The correct option is D Change in mass

A chemical reaction is characterized by:
Change in temperature
Change in colour
Change in state
Evolution of gas
Formation of precipitate
Formation of new substance
Clearly options a, b and c are the characteristics of a chemical reaction that are observed in a chemical change. The law of conservation of mass states that mass can neither be created nor destroyed during a chemical reaction. Hence,change in mass is not observed in a chemical change.