The average translational kinetic energy of 10 gram H₂ at 27 °C is

Average translational kinetic energy of a gas is given as
$\mathrm{KE}=\frac{3}{2}\mathrm{nRT}$, where n is number of moles of gas, R is universal gas constant and T is absolute temperature of gas.
$\begin{array}{l}\mathrm{KE}=\frac{3}{2}\times 5\times \frac{25}{3}\times 300\mathrm{J}\\ \mathrm{KE}=18750\mathrm{J}\end{array}$
Hence, average translational kinetic energy of gas is 18750 J.