c
(c)\({C_{(s)}} + 2{H_2}_{(g)} \to C{H_{4(g)}}\)…..\((i)\) \({C_{(s)}} + {O_{2(g)}} \to C{O_{2(g)}}\,\,\,\Delta H = - 94\,kcal\,mo{l^{ - 1}}\)…..\((ii)\) \({H_{2(g)}} + \frac{1}{2}{O_{2(g)}} \to {H_2}{O_{(l)}}\,\,\,\Delta H = - 68\,kcal\,mo{l^{ - 1}}\)…\((iii)\) \(C{H_4} + 3{/_2}{O_2} \to C{O_2} + 2{H_2}O\) \(\Delta H = - 213\,kcal\,mo{l^{ - 1}}\)… \((iv)\) to obtain equation \((i)\) operate\(-(ii) + 2 × (iii) -(iv)\)