The melting point of solid MgO (2,852 °C) is far higher than that of solid NaF (993 °C)
CHEMISTRY · Single correct · CBSE · Chemistry · Chemical Bonding and Molecular Structure · Chemical Bonding and Molecular Structure
Problem
The melting point of solid MgO (2,852 °C) is far higher than that of solid NaF (993 °C). Which of the following best explains this difference?
(a) MgO has a higher molar mass than NaF, so more thermal energy is required to make its heavier ions move apart when melting.
(b) The electronegativity difference between Mg and O is greater than that between Na and F, making the Mg–O bond more polar and therefore stronger.
(c) The ions in MgO carry larger charges and have smaller radii than those in NaF, leading to much stronger electrostatic attractions.
(d) Each O2− ion in MgO is surrounded by more cations than each F− ion in NaF, so more bonds must be broken to melt MgO.