Question

Which of the following statements best explains the law of conservation of mass?

• A. $100 \,g$ of water is heated to give steam
• B. A sample of $N_2$ gas is heated at constant pressure without any change in mass
• C. $36 \,g $ of carbon combines with $32\, g$ of oxygen to form $68 \,g$ of $CO_2$
• D. $10 \,g$ of carbon is heated in vacuum without any change in mass

Answer 1

Answer: (C)

According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
Among the given option only option C involves a chemical change/reaction as:
$\underset{2}{C + O} \rightarrow \underset{2}{CO}$
and $m_{\text{reactants}}= m_{\text{products}}$
$36+32=68\, g$