Internal energy is

When $2$ moles of an ideal gas are expanded isothermally from a volume of $12.5 \ L$ to $15.0 \ L$ against a constant external pressure of $760 \ mm \ Hg$,calculate the amount of work done in joules. (in $J$)

Assertion : Absolute values of internal energy of substances cannot be determined.
Reason : It is impossible to determine exact values of constituent energies of the substances.

$2 \ \text{moles}$ of a gas undergoes a change in state from $(2 \ \text{bar}, 40 \ \text{L})$ to $(5 \ \text{bar}, 15 \ \text{L})$ at a constant temperature. If the change in internal energy is given by $35 \ \text{bar-L}$, then the enthalpy change for the process will be: (in $\text{bar-L}$)

The value of $\Delta H - \Delta E$ for the following reaction at $27 \ ^\circ C$ will be $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}$

If a system neither gains nor loses heat during its transformation from one state to another,such a process is called ......