Question

Law of conservation of mass states that during a chemical reaction,

• A. mass remains unchanged
• B. volume remains unchanged
• C. temperature remains unchanged
• D. none of these

Answer 1

The correct option is A

mass remains unchanged

Law of conservation of mass-

• The Law of conservation of mass states that during a chemical reaction, mass can neither be created nor be destroyed.
• According to this law, the total mass of the reactants should be equal to the total mass of the products.
• Hence, mass remains unchanged during a chemical reaction.
• Let us understand with an example of carbon burning in presence of oxygen to form carbon dioxide.
• $\underset{\mathrm{Carbon}}{\mathrm{C}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{burning}}{\to }\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}$
• Here, the mass of reactants is equal to the mass of the product according to the law of conservation of mass.

Hence, option (A) mass remains unchanged is the correct answer.