Internal energy of n₁ mol of hydrogen of temperature T is equal to the internal energy n₂ mol of helium at temperature 2T. The ratio n₁/n₂ is : 

\(\frac{6}{5}\)

Internal energy of n moles of an ideal gas at temperature T is given by : 

\(U = \frac{f}{2} nRT\)

\(U_1 = U_2\)

\(f_1 n_1 T_1 = f_2 n_2 T_2\)

\(\frac{n_1}{n_2} = \frac{f_2 T_2}{f_1 T_1}\)

\(\frac{3*2}{5*1} = \frac{6}{5}\)

Here, f₂ = degrees of freedom of He = 3

and, f₁ = degrees of freedom of H₂ = 5