Which of the following crystalline solids conduct electricity in molten state but not in solid state?

Options

A. Ionic crystals
B. Molecular crystals
C. Covalent crystals
D. Metallic crystals

Answer

1

Explanation

In ionic crystals the ions are not free to have translational or rotational motion but can only vibrate about their mean equilibrium positive on account of strong coulombic( elctrostatic ) forces . But in the molten state the ions are free to execute translatory as well as rotatory motion,This facilitates ocndution of electricity.
Most ionic crystals have high melting points an indication of the strong cohesive force holding the ions together .A measure of the stability of ionic crystals is the lattice enthalpy : the highest the lattice enthalpy the more stable the compound. However introduction of covalent character due to polarization decreases the stability.