$A$ certain system is exothermic by $260 \ kJ$ and does $10 \ kJ$ of work. What is the change in internal energy (in $kJ$)?

When a gas undergoes adiabatic expansion,it cools down because:

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 $J$)?

If the internal energy of an ideal gas decreases by the same amount of the work done by the system,the process is

Calculate $\Delta H$ for the following reaction at $25^{\circ} C$.
$NH_2CN_{(g)} + \frac{3}{2} O_{2_{(g)}} \longrightarrow N_{2_{(g)}} + CO_{2_{(g)}} + H_2O_{(l)}$
$(\Delta U = -740.5 \ kJ, R = 8.314 \ J \ K^{-1} \ mol^{-1})$

Based on the first law of thermodynamics,which one of the following is correct?