Consider the reactions given below. On the basis of these reactions find out which of the algebric relations given in options (I) to (iv) is correct?

(a) C (g) + 4 H (g) → CH4 (g); ΔrH = x kJ mol–1


(b) C (graphite, s) + 2H2 (g) → CH4 (g); ΔrH = y kJ mol–1


Reason: Same bonds are formed in both the reaction but in the second reaction there is breaking of bond take place in which energy is absorbed.

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