Answer:
a. Br2 (l) → Br2(g) ΔH°rxn = 30.91 kJ/mol
Explanation:
Bond enthalpy is the energy which is required to break 1 mol of of bonds in gaseous covalent molecules. Bond breaking process can be endothermic or exothermic depending on the molecules association. The process needs to be performed in chemical laboratory under standard conditions.