Enthalpy change for the reaction,4Hg⟶2H2(g) is -869.6 kJ.The dissociation energy of H-H bond is-
If at 298 K the bond energies of C - H, C - C, C=C and H - H bonds are respectively 414, 347, 615 and 435 kJ mol−1, the value of enthalpy change for the reaction