An electric heater supplies heat to a system at a rate of $100\;W.$ If the system performs work at a rate of $75\;J/s,$ at what rate (in $J/s$) is the internal energy increasing?

The change in the internal energy of a mass of gas,when the volume changes from $V$ to $2V$ at constant pressure $P$,is given by (where $\gamma = C_P / C_V$):

Consider $1 \,kg$ of liquid water undergoing a change in phase to water vapour at $100^{\circ} C$. At $100^{\circ} C$,the vapour pressure is $1.01 \times 10^5 \,N m^{-2}$ and the latent heat of vaporization is $22.6 \times 10^5 \,J kg^{-1}$. The density of liquid water is $10^3 \,kg m^{-3}$ and that of vapour is $\frac{1}{1.8} \,kg m^{-3}$. The change in internal energy in this phase change is nearly ............ $J kg^{-1}$.

$A$ gas is compressed at a constant pressure of $50 \ N/m^{2}$ from a volume of $10 \ m^{3}$ to $4 \ m^{3}$. Then,the gas is heated by supplying $100 \ J$ of energy. The increase in its internal energy will be ..... $J$.

$1 \text{ cm}^3$ of water at its boiling point absorbs $540 \text{ calories}$ of heat to become steam with a volume of $1671 \text{ cm}^3$. If the atmospheric pressure = $1.013 \times 10^5 \text{ N/m}^2$ and the mechanical equivalent of heat = $4.19 \text{ J/calorie}$, the energy spent in this process in overcoming intermolecular forces is ..... $\text{cal}$. (in $\text{cal}$)

The increase in internal energy of $2$ moles of gas when its temperature is raised from $340 \ K$ to $342 \ K$ is ........ $cal$. Given $C_v = 4.96 \ cal/mole \ K$.