Question

Which of the following is not an observation that determines a chemical change?

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

Answer 1

The correct option is D

Change in mass
Evolution of a gas, change in state, change in colour and change in temperature are the observations that help to determine whether a chemical reaction has taken place or not. The change in mass of a substance may not necessarily mean that a chemical reaction has taken place. It can be attributed to a physical change also.

Hence, the correct answer is option (d).