Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom.The gas is maintained at a temperature of T. The total internal energy, U of a mole of this gas, and the value of
$\gamma \left( { = {{{C_p}} \over {{C_v}}}} \right)$ are given, respectively by:

1. A U = ${5 \over 2}RT$ and $\gamma = {7 \over 5}$ Correct answer
2. B U = 5RT and $\gamma = {6 \over 5}$
3. C U = 5RT and $\gamma = {7 \over 5}$
4. D U = ${5 \over 2}RT$ and $\gamma = {6 \over 5}$