Three moles of an ideal gas expand reversibly under isothermal conditions from $2 \, L$ to $20 \, L$ at $300 \, K$. The amount of heat change (in $kJ / mol$) in the process is:

$A$ sample of gas absorbs $4000 \ kJ$ of heat and the surrounding does $2000 \ J$ of work on the sample. What is the value of $\Delta U$ (in $kJ$)?

The $\Delta U^o$ of combustion of $CH_{4(g)}$ at a certain temperature is $-393 \ kJ/mol$. Then the value of $\Delta H^o$ is:

At the $1$ bar pressure,the volume of a gas is $0.6 \ L$. If the gas receives $122 \ J$ of heat at $1$ bar pressure,the volume becomes $2 \ L$. Calculate the change in its internal energy. $(1 \ L \cdot bar = 101.32 \ J)$

$2 \ mol$ of an ideal gas are expanded isothermally and reversibly from $20 \ L$ to $40 \ L$ at $300 \ K$. Calculate work done. $(R=8.314 \ J \ K^{-1} \ mol^{-1})$ (in $J$)

$A$ heat engine absorbs heat $Q_1$ at temperature $T_1$ and heat $Q_2$ at temperature $T_2$. Work done by the engine is $(Q_1 + Q_2)$. This data