The temperature of a system decreases in which of the following processes?

$A$ gas expands isothermally from $10 \, dm^3$ to $20 \, dm^3$ at a constant external pressure of $1 \, atm$. If it absorbs $800 \, J$ of heat from the surroundings,what is the value of $\Delta U$ in $J$ for this process?

For the combustion of sucrose $(C_{12}H_{22}O_{11})$ at $250\,^oC$,which of the following is true?

In a $1 \, L$ container,$2 \, mol$ of $CO$ and $1 \, mol$ of $O_2$ are taken. They react according to the equation: $2CO(g) + O_2(g) \rightarrow 2CO_2(g)$,$\Delta H = -560 \, kJ$. Given that $1 \, atm \cdot L = 0.1 \, kJ$,and the pressure changes from $70 \, atm$ to $40 \, atm$ at $500 \, K$,calculate the value of $\Delta U$ in $kJ$.

In a process,a system performs $238 \ J$ of work on its surroundings by absorbing $54 \ J$ of heat. What is the change in internal energy of the system during this operation (in $J$)?

Calculate $\Delta H$ for the following reaction at $300 \text{ K}$: $2C(s) + 3H_2(g) \rightarrow C_2H_6(g)$ if $\Delta U$ for the reaction is $-80 \text{ kJ}$ $(R = 8.314 \text{ J K}^{-1} \text{mol}^{-1})$ (in $\text{ kJ}$)