We know that kinetic energy is given by, $\mathrm{KE}=\frac{1}{2}{\mathrm{mv}}_{\mathrm{rms}}^2$

And ${\mathrm{v}}_{\mathrm{rms}}=\sqrt{\frac{3\mathrm{RT}}{\mathrm{m}}}$

So, the average kinetic energy of $\text{'}\mathrm{n}\text{'}$ moles of a gas is given by,

$\mathrm{KE}=\frac{3}{2}\mathrm{nRT}$

$=\frac{3}{2}\times 1\times 8.314\times (27+273) \mathrm{J}$

$=\frac{3}{2}\times 8.314\times 300 \mathrm{J}$

$=3741.3 \mathrm{J}$.