What is the change in internal energy when a system releases $8 \ kJ$ of heat and performs $660 \ J$ of work on the surroundings (in $J$)?

For the reaction,$N_{2(g)} + 3 H_{2(g)} \rightarrow 2 NH_{3(g)}$,$\Delta H$ is equal to

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

For combustion of one mole of magnesium in an open container at $300 \ K$ and $1 \ bar$ pressure,$\Delta_{C}H^{\ominus} = -601.70 \ kJ \ mol^{-1}$,the magnitude of change in internal energy for the reaction is $.... \ kJ$. (Nearest integer)
(Given : $R = 8.3 \ J \ K^{-1} \ mol^{-1}$ )

The $\Delta U^{\theta}$ of combustion of methane is $-X \ kJ \ mol^{-1}.$ The value of $\Delta H^{\theta}$ is

One mole of gas absorbs $200 \ J$ of heat at constant volume,then its temperature rises from $298 \ K$ to $308 \ K$. The change in internal energy will be $... \ J$.