$A$ thermodynamic system absorbs $2 \, kcal$ of heat and performs $500 \, J$ of work. The change in its internal energy is ......... $J$.

Write and explain the first law of thermodynamics.

$A$ source supplies heat to a system at the rate of $1000 \, W$. If the system performs work at a rate of $200 \, W$,the rate at which the internal energy of the system increases is $....... \, W$.

In a given process,for an ideal gas,$\Delta W = 0$ and $\Delta Q < 0$. Then,for the gas,

$A$ 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 the relation between $\Delta U_1$ and $\Delta U_2$ is

$1 \text{ cm}^3$ 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 $\text{cal}$)