Question

The image above could be representative of a solid sample of $NaCl$. If the sample shown were actually $MgO$, the melting point would increase.
What is the reason for this change in melting point?

• A. The difference in radii between $M{g}^{2+}$ and $O^{2-}$ ions is larger.
• B. The electrostatic attraction between $M{g}^{2+}$ and $O^{2-}$ ions is stronger.
• C. The electrostatic attraction between $M{g}^{2+}$ and $O^{2-}$ ions weaker.
• D. The difference in radii between $M{g}^{2+}$ and $O^{2-}$ ions is smaller.

Answer 1

The correct option is B The electrostatic attraction between $M{g}^{2+}$ and $O^{2-}$ ions is stronger.

Force of electrostatic attraction between the charges is directly proportional to multiplication of charges. Charge of Mg is 2+ and Charge of O is -2. Charge on ions of Na and K is +1 and charge on Cl ion is -1. So the multiplication of charge will be more for MgO.For greater attraction forces meting point increases.