Question

A cylinder of 10 L capacity at 300 K containing the He gas is used to fill balloons. The cylinder recorded a pressure of ${10}^{-2}$ bar. The number of He atoms present in the cylinder is :

• A. $4.82\times {10}^{21}$
• B. $2.41\times {10}^{23}$
• C. $2.41\times {10}^{21}$
• D. $4.82\times {10}^{23}$

Answer 1

Answer: (C)

$2.41\times {10}^{21}$

According to the ideal gas equation,
$PV=nRT$

Given,

$P={10}^{-2}bar$

$V=10L$

$T=300K$

Putting these value in equation,
$n=\frac{PV}{RT}$

$=\frac{{10}^{-2}\times 10}{8.314\times {10}^{-2}\times 300}$

$NumberofHeatoms=n\times N_A$

$=\frac{{10}^{-2}\times 10\times 6.023\times {10}^{23}}{0.083\times 300}$

$=2.41\times {10}^{21}$ atoms

Hence, option $\left(C\right)$ is correct.