What is the amount of work done when $0.5 \ mol$ of methane,$CH_{4(g)}$,is subjected to combustion at $300 \ K$? (Given: $R = 8.314 \ J \ K^{-1} \ mol^{-1}$)

When a gas undergoes adiabatic expansion,it gets cooled due to

The gas absorbs $100 \ J$ and is simultaneously compressed by a constant external pressure of $1.50 \ atm$ from $8 \ L$ to $2 \ L$ volume. Hence $\Delta U$ will be ..... $J$.

$4.0 \, L$ of an ideal gas is allowed to expand isothermally into vacuum until the total volume is $20 \, L$. The amount of heat absorbed in this expansion is $..... \, L \, atm$.

An ideal gas,$\overline{C}_{V} = \frac{5}{2} R$,is expanded adiabatically against a constant pressure of $1 \ atm$ until it doubles in volume. If the initial temperature and pressure are $298 \ K$ and $5 \ atm$,respectively,then the final temperature is . . . . . . $K$ (nearest integer). [$\overline{C}_{V}$ is the molar heat capacity at constant volume]

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? $[R = 8.314 \ J \ K^{-1} \ mol^{-1}]$