Q74 / 180 · AIIMS 2002 · Chemistry
Assertion : Atoms can neither be created nor destroyed.
Reason : Under similar condition of temperature and pressure, equal volume of gases does not contain equal number of atoms.
- AIf both the assertion and reason are true and reason is a correct explanation of the assertion.
- BIf both assertion and reason are true but assertion is not a correct explanation of the assertion.
- Correct answerCIf the assertion is true but the reason is false.
- DIf both assertion and reason are false.
Solution
Atoms can neither be created nor destroyed. This is the statement of law of conservation of mass. Under similar conditions of temperature and pressure, equal volume of gases contain equal number of atoms. As, $P V=n R T$ (Ideal gas equation)
If, for Ist case, for IInd case,
$$
\begin{aligned}
& P_1 V_1=n_1 R T_1 \\
& P_2 V_2=n_2 R T_2
\end{aligned}
$$
$$
\Rightarrow \quad \frac{P_1 V_1}{P_2 V_2}=\frac{n_1 R T_1}{n_2 R T_2} \Rightarrow n_1=n_2\left(\because P_1,=P_2, V_1=V_2, T_1=T_2\right)
$$
Hence, the correct answer is option: 'C'.