${H_2}O(g) + C(s) \to CO(g) + {H_2}(g);\,\Delta H = 131\,kJ$$CO(g) + \frac{1}{2}{O_2}(g) \to C{O_2}(g);\Delta H = - 282\,kJ$
${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(g);\,\Delta H = - 242\,kJ$
$C(s) + {O_2}(g) \to C{O_2}(g);\,\Delta H = X\,kJ$
$X$ નું મૂલ્ય ......$kJ$

$(i)\,\,\Delta H_f^o\,\,of\,{H_2}{O_{(\ell )}}\, = \,\, - 68.3\,K\,\,cal\,\,mo{l^{ - 1}}$
$(ii)\,\,\Delta H_{comb}^o\,\,of\,{C_2}{H_2}\, = \,\, - 337.2\,K\,\,cal\,\,mo{l^{ - 1}}$
$(iii)\,\,\Delta H_{comb}^o\,\,of\,\,{C_2}{H_4}\,\, = \,\, - \,363.7\,\,K\,\,cal\,\,mo{l^{ - 1}} $