If one atom of an element $X$ weighs $6.643 \times 10^{-23} \mathrm{~g}$. Then, find the number of moles of…
If one atom of an element $X$ weighs $6.643 \times 10^{-23} \mathrm{~g}$. Then, find the number of moles of atoms in $50 \mathrm{~kg}$ of element $X$.
- 500 moles
- 125 moles
- 1250 moles
- 50 moles
Solution
Number of atoms in $50 \mathrm{~kg}=\frac{50 \times 1000}{6.643 \times 10^{-23}}$
$
=\frac{50000 \times 10^{23}}{6.643} \text { atoms }
$
$
\begin{aligned}
\text { Number of moles } & =\frac{\text { Number of atoms }}{\text { Avogadro's Number }} \\
& =\frac{50000 \times 10^{23}}{6.643 \times 6.02 \times 10^{23}} \\
& =1250.3 \mathrm{moles} \simeq 1250 \mathrm{moles}
\end{aligned}
$
Asked in: AP EAMCET 2021 (23 Aug Shift 1)
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