Explain why the melting point of magnesium oxide, MgO, is much higher than that of those in sodium chloride, NaCl.
Magnesium ions have a greater charge than sodium ions.
Oxide ions have a greater charge than chloride ions.
The electrostatic attraction between oppositely charged ions is much greater in MgO than it is in NaCl.
The ionic bonding is much stronger in MgO than it is in NaCl.