$A$ 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 ..... $J$.

$1.00 \ kg$ of liquid water at $100^{\circ} C$ undergoes a phase change into steam at $100^{\circ} C$ at $1.0 \ atm$ (take it to be $1.00 \times 10^5 \ Pa$). The initial volume of the liquid water was $1.00 \times 10^{-3} \ m^3$ which is changed to $2.001 \ m^3$ of steam. Find the change in the internal energy of the system. [Use heat of vaporization $\simeq 2000 \ kJ \ kg^{-1}$] (in $kJ$)

$A$ sample of $0.1 \, g$ of water at $100^{\circ} C$ and normal pressure $(1.013 \times 10^5 \, N m^{-2})$ requires $54 \, cal$ of heat energy to convert to steam at $100^{\circ} C$. If the volume of the steam produced is $167.1 \, cc$,the change in internal energy of the sample is ....... $J$.

Is it possible to convert internal energy into work or mechanical energy?

Why does a gas get heated on compression?

Density of water at $4 ^\circ C$ and $20 ^\circ C$ are $1000 \ kg/m^3$ and $998 \ kg/m^3$ respectively. The increase in internal energy of $4 \ kg$ water when it is heated from $4 ^\circ C$ to $20 ^\circ C$ is . . . . . . $J$. (Specific heat capacity of water $= 4.2 \ kJ/kg \cdot K$ and $1$ atmospheric pressure $= 10^5 \ Pa$)