The difference between $\Delta H$ and $\Delta U$ $(\Delta H - \Delta U),$ when the combustion of one mole of heptane $(l)$ is carried out at a temperature $T$ is equal to (in $,RT$)

Consider the following statements:
Statement-$I$: During isothermal expansion of an ideal gas,its enthalpy decreases.
Statement-$II$: When $2.0 \ L$ of an ideal gas expands isothermally into vacuum,$\Delta U = 0$.

Calculate the work done in $kJ$ when $3$ moles of an ideal gas at $27^{\circ} C$ expand isothermally and reversibly from $10 \ atm$ to $1 \ atm$ $[R=8.314 \ J \ K^{-1} \ mol^{-1}]$

The heat of combustion $\left(kJ \ mol^{-1}\right)$ is highest for

The heat liberated when $1.89 \ g$ of benzoic acid is burnt in a bomb calorimeter at $25 \ ^\circ C$ increases the temperature of $18.94 \ kg$ of water by $0.632 \ ^\circ C$. If the specific heat of water at $25 \ ^\circ C$ is $0.998 \ cal/g \cdot ^\circ C$,the value of the heat of combustion of benzoic acid is .... $kcal/mol$. (Molar mass of benzoic acid = $122 \ g/mol$)

For a spontaneous process, the correct statement$(s)$ is (are):