Q73 / 180 · AIIMS 2002 · Chemistry
The weight of one molecule of a compound $\mathrm{C}_{60} \mathrm{H}_{122}$ is
- A$1.2 \times 10^{-20} \mathrm{~g}$
- B$5.025 \times 10^{23} \mathrm{~g}$
- Correct answerC$1.4 \times 10^{-21} \mathrm{~g}$
- D$6.023 \times 10^{23} \mathrm{~g}$.
Solution
$$
\begin{aligned}
& \text { Molecular weight of } \mathrm{C}_{60} \mathrm{H}_{122}=60 \times 12+1 \times 122 \\
& =842 \mathrm{~g} \mathrm{~mol}^{-1} \\
& \therefore \text { Weight of } 1 \text { mole of } \mathrm{C}_{60} \mathrm{H}_{122} \text { molecules }=842 \mathrm{~g} \\
& \Rightarrow \text { Weight of } 6.023 \times 10^{23} \text { molecules } \quad=842 \mathrm{~g} \\
& \Rightarrow \text { Weight of } 1 \text { molecule }=\frac{842}{6.023 \times 10^{23}} \\
& =1.4 \times 10^{-21} \mathrm{~g} \\
&
\end{aligned}
$$
Hence, the correct answer is option: 'C'.