Question

Consider the following statements about a chemical reaction. Which one is true?

• A. The total number of molecules remains unchanged
• B. The total number of moles remains the same
• C. The total mass is not altered
• D. The total number of reaction molecules is equal to the total number of molecules of the products formed

Answer 1

Answer: (C)

The total mass is not altered

A number of molecules or moles may get change in a chemical reaction. Also, the number of reactant molecules need not be equal to product molecules. They may get less if association reaction takes place or they may get increase due to dissociation reaction.

But, according to the law of mass conservation, for any chemical reaction, the total mass remains constant at all times.

Hence, Option $C$ is correct.