A Question

The fact mp of NaCl >mp of MgCl >mp Of AlCl3 is clear match with the ionic force between each element . The ionic force of NaCl >MgCl2>AlCl3 . Also this is due to the single valance of sodium one to one attraction to chloride , but magesium to 2 chlorides & aluminium to 3 chlorides . From this the attraction is going down . When you melt NaCl you need to supply more energy to pull sodium & chlorine apart but less for magesium chloride , similarly for aluminium chloride .