Calculate the difference between $\Delta H$ and $\Delta U$ for the combustion of $n$-octane at $25^{\circ}C$. (in $kJ$)

If a system absorbs $30 \ kJ$ of heat and performs $12 \ kJ$ of work on the surroundings,what is the increase in internal energy of the system (in $kJ$)?

$A$ gas in a frictionless piston cylinder at a constant pressure of $1 \ atm$ expands from a volume of $2 \ L$ to $6 \ L$. In doing so,it absorbs $800 \ J$ of heat from the surroundings. The change in internal energy of the process is ..... $J$.

For an ideal gas,the heat of reaction at constant pressure and heat of reaction at constant volume are related by the equation:

Assertion : For a reaction $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}$ ; $\Delta H > \Delta E$.
Reason : Enthalpy change is always greater than internal energy change.

At $298 \ K$,what is the value of $\Delta H - \Delta E$ in $J \ mol^{-1}$ when $1 \ mol$ of carbon monoxide gas is formed from its elements in their standard states? $[R = 8.314 \ J \ K^{-1} \ mol^{-1}]$