Which of the following ionic compounds should have the highest melting point?
A)NaI
B)MgO
C)NaCl
D)LiBr
E)CaS

Question

Quizplus · Accepted Answer

Ionic compounds have high melting points due to the strong electrostatic attraction between the cations and anions. The compound with the highest charge on the ions and/or the smallest ion size will have the strongest attraction and therefore the highest melting point. 
Out of the given options, MgO has the highest charge on its ions (+2 and -2) and its ions are smaller in size than those in CaS, making it the most strongly bonded and hence having the highest melting point.

Which of the Following Ionic Compounds Should Have the Highest