Question

Assertion (A): A pair of electrons not shared with any other atom is known as a lone pair.

Reason (R): Ammonium ion has a lone pair.

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and R are true but R is not the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

A is true but R is false.

Explanation:

The term lone pair of electrons refers to an unshared pair of electrons. Therefore, the assertion (A) is accurate. Ammonium molecules, not ammonium ions, have a single pair of electrons. When the hydrogen ion accepts the lone pair of electrons on the nitrogen atom in the ammonium molecule and creates a coordinate bond, an ammonium ion is created. Thus, there are no remaining lone pairs of electrons. Reason (R) is therefore untrue.