$A$ system is given $300$ calories of heat and it does $600$ joules of work. How much does the internal energy of the system change in this process? $(1 \text{ calorie} = 4.18 \text{ joules})$

If the heat given to a system is $35 \ J$ and the work done on the system is $15 \ J$,then the change in the internal energy of the system is ... $J$?

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

$540$ calories of heat convert $1$ cubic centimeter of water at $100^{\circ}C$ into $1671$ cubic centimeter of steam at $100^{\circ}C$ at a pressure of one atmosphere. Then the work done against the atmospheric pressure is nearly ...... $cal$.

$A$ gas is supplied with $1500 \; J$ of heat energy at constant pressure. If the constant pressure of the gas is $2.1 \times 10^{5} \; N/m^{2}$ and the increase in volume is $2.5 \times 10^{-3} \; m^{3}$,then the increase in the internal energy of the gas is ...... $J$.

The volume of a gas at a constant pressure of $50\,N/m^2$ changes from $10\,m^3$ to $4\,m^3$. If $100\,J$ of heat is supplied to the gas,the increase in internal energy is ....... $J$.