What is the value of $\Delta H - \Delta U$ for the formation of $2$ moles of ammonia from $H_{2(g)}$ and $N_{2(g)}$?

Which of the following is the correct mathematical expression for the first law of thermodynamics?

$A$ gas absorbs $200 \ J$ of heat and expands by $500 \ cm^3$ against a constant external pressure of $2 \times 10^5 \ N \ m^{-2}$. What is the change in internal energy (in $J$)?

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.

If $5 \ kJ$ of work is done on the system and $1 \ kJ$ of heat is released by the system,find the change in internal energy in $kJ$.

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 $\text{ kJ}$)