Internal Energy Questions

A system goes from A to B via two processes I and II as shown in the figure. If $\Delta U_1$ and $\Delta U_2$ are the changes in internal energies in the processes I and II respectively, then:

One kg of a diatomic gas is at a pressure of $8\times 10^4{\text{N/m}}^2$. The density of the gas is $4{\text{kg/m}}^3$. What is the energy of the gas due to its thermal motion?

$100\text{g}$ of water is heated from $30^{\circ }\text{C}$ to $50^{\circ }\text{C}$. Ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is $4184\text{J/kg/K}$):