Question

Explanations for the higher melting point of MgO compared to NaF include:

I. Mg2+ is more positively charged than Na+
II. O2− is more negatively charged than F−
III. The O2− ion is smaller than the F− ion
(A) II only
(B) I and II only
(C) I and III only
(D) II and III only
(E) I, II, and III"

Answer 1

The higher melting point of MgO compared to NaF can be explained by the higher positive charge of Mg2+ ion, the higher negative charge of O2- ion, and the smaller size of O2- ion compared to F- ion.

Step-by-step explanation:

The higher melting point of MgO compared to NaF can be explained by multiple factors:

1. Mg2+ is more positively charged than Na+: The higher charge on the Mg2+ ion results in stronger electrostatic attractions between the ions in the crystal lattice of MgO, leading to higher melting point.
2. O2- is more negatively charged than F-: Similarly, the higher charge on the O2- ion in MgO leads to stronger electrostatic attractions compared to NaF, contributing to a higher melting point.
3. The O2- ion is smaller than the F- ion: The smaller size of the O2- ion allows for closer packing in the crystal lattice, resulting in stronger ion-ion interactions and a higher melting point compared to NaF.

Therefore, the correct answer is (E) I, II, and III.