For cyclic process : $\Delta U = 0 \Rightarrow q = - w$
For isothermal process : $\Delta U = 0 \Rightarrow q = - w$
For adiabatic process : $q = 0 \Rightarrow \Delta U = W$
For isochoric process : $w = 0 \Rightarrow \Delta U = q$
$2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_2(\mathrm{~g}) 2 \mathrm{CO}_2(\mathrm{~g}), \Delta \mathrm{H}=-787 \mathrm{KJ} ; \mathrm{H}_2(\mathrm{~g})+$$\mathrm{H}_2 \mathrm{O}, \Delta \mathrm{H}=-286 \mathrm{KJ}$
$\frac{1}{2} \mathrm{O}_2 \mathrm{C}_2 \mathrm{H}_2(g)+\frac{5}{2} \mathrm{O}_2(g) \rightarrow 2 \mathrm{CO}_2(g)+\mathrm{H}_2 \mathrm{O}(I), \Delta H=-1310KJ$