Question:
The number of molecules in one litre of an ideal gas at $300 \mathrm{~K}$ and 2 atmospheric pressure with mean kinetic energy $2 \times 10^{-9} \mathrm{~J}$ per molecules is :
Correct Option: , 3
Solution:
$\mathrm{KE}=\frac{3}{2} \mathrm{kT}$
$\mathrm{PV}=\frac{\mathrm{N}}{\mathrm{N}_{\mathrm{A}}} \mathrm{RT}$
$\mathrm{N}=\frac{\mathrm{PV}}{\mathrm{kT}}$
$=\mathrm{N}=1.5 \times 10^{11}$