Question

Pure water is a poor conductor of electricity. When sodium chloride (NaCl) is dissolved in water, however, the solution becomes a good conductor of electricity. Which of the following statements explains this change in conductivity?

A.
The NaCl molecule changes and becomes a covalent bond when dissolved in water.
B.
The NaCl dissociates into Na+ and Cl- ions, which are able to carry the charge.
C.
The NaCl breaks down the water molecules creating charged oxygen and hydrogen ions.
D.
The NaCl reacts with water to form the electrically charged compounds HCl and Na2O.

Answer 1

Answer: Option (B) is the correct answer.

Explanation:

NaCl is a polar compound as it contains an ionic bond between sodium atom and chlorine atom.

Also, it is known that like dissolves like. So, when we add NaCl in water then sodium chloride will dissociate into ions as it will form $Na^{+}$ ions and $Cl^{-}$ ions.

These ions will help in the flow of electrons when electric current is passed through a solution of NaCl.

Thus, we can conclude that the statement, the NaCl dissociates into $Na^{+}$ and $Cl^{-}$ ions, which are able to carry the charge.