Answer:
Option D is correct. MgO has a higher melting point because the ions have larger charges.
Explanation:
Magnesium oxide contains higher melting point compare to sodium chloride, because of its Mg2+, and O2- ions contain greater number of charges, and helping to form strong ionic bonds compare to Na+, and Cl- ions in Nacl.
That's why melting point of magnesium oxide is more than sodium chloride. MgO molecules bounded with each other with very high force known as electrostatic attraction present between negatively charge oxygen, and positively charge magnesium ions.
