See explanation below.
Work Step by Step
A) The standard enthalpy will value according to the numbered for ease of solution. B) Suggests that energy is taken in when form the bond rtp. Therefore, energy must be given up too break that bond. C) Mg + Cl2 > MgCl2 D) Yes, this method is favored because the greater the lattice energy, the more energy that will be required to break the bond.