Question

Identify the pair of electrolytes in which, one contains only ions and the other contains unionized molecules in addition to ions respectively.
(A) potassium hydroxide, nitric acid
(B) carbonic acid, potassium chloride
(C) sodium hydroxide, carbonic acid
(D) barium sulphate, acetic acid

Answer 1

A molecule is said to be ionized if it dissociates into ions when dissolved in any polar/non-polar solvents and is said to be unionized if it doesn't dissociate on dissolving in polar/non-polar solvent into its ions. Now, you can easily identify it.

Complete step by step solution:
First of all we should know what electrolytes are. Electrolytes are the substances which when dissolved into any liquid medium, they get split into the ions and that ions carries the positive and the negative charge respectively. These ions, then , in that liquid medium i.e. the solution helps to conduct the electricity.
This process is known as ionization . So, we may define ionization as the process by which the neutral atoms or molecules (which are electrically inactive ) becomes actively charged atoms or molecules. Example ; consider the ionization of HCl with water, HCl loses the hydrogen atom which is gained by the water molecule and thus, forms hydronium ion having positive charge on it and chloride ion gets negative charge. So, these ions become electrically charged now and are called ionized ions.
On the other hand, in unionized molecules, the molecules do not dissociate into the electrically charged ions (i.e. the anions and cations).
So, considering the above definitions, it is clear that potassium hydroxide contains only ions and nitric acid contains ions but is a unionized molecule.
Whereas, carbonic acid is an ionized anion, potassium chloride , sodium hydroxide, barium sulphate and acetic acid all are ionized molecules.

Hence, option (A) is correct.

Note: Nitric acid may consist of the ions but is not ionized into the ions when it is dissolved in the any polar solvent such as water or any non-polar solvent such as benzene etc. on the other hand, ionized molecules dissociate when dissolved in water, acid /alkali into its corresponding ions.