The correct match is A-II, B-III, C-I, D-IV Bond enthalpy also known as bond dissociation energy describes the amount of energy stored in a bond between atoms in a molecules. Specifically it is the energy required to be added for cleavage of bond in a gas phase. ‌Si−Si→297kJ∕mol ‌C−C→348kJ∕mol ‌Sn−Sn→248kJ∕mol ‌Ge−Ge→260kJ∕mol Down the group, bond enthalpy decreases.