Which compound in each of the following pairs of ionic substances has the most exothermic lattice energy? Justify your answers.
a. $\mathrm{NaCl}, \mathrm{KCl} \quad$ d. Fe $(\mathrm{OH})_{2}, \mathrm{Fe}(\mathrm{OH})_{3}$
b. $\mathrm{LiF}, \mathrm{LiCl} \quad$ e. $\mathrm{NaCl}, \mathrm{Na}_{2} \mathrm{O}$
c. $\mathrm{Mg}(\mathrm{OH})_{2}, \mathrm{MgO} \quad$ f. $\mathrm{MgO}, \mathrm{BaS}$