Question

Molten sodium chloride conducts electric current due to the presence of:

• A. free electrons
• B. free mobile ions
• C. immobile ions
• D. none of these

Answer 1

Answer: (B)

free mobile ions

Current is the rate of flow of charge. NaCl is an ionic solid. An ionic solid consists of a lattice of ${Na}^{+}$ and ${Cl}^{-}$ ions in which these ions are fixed in their places. Solid NaCl does not contain any mobile charge carriers that can facilitate the flow of charge. But molten NaCl contains free mobile ions ${Na}^{+}$ and ${Cl}^{-}$ ions which allow the passage of current.

Thus, molten NaCl conducts electric current due to the presence of free mobile ions.