Which of the following element is not regarded as a transition metal?

The correct answer is Option (4) → Zn

A transition metal is defined as a metal that has an incomplete d subshell either in its neutral atom or in its ions. Zinc, cadmium and mercury have a full d¹⁰ configuration in the ground state and in their common oxidation state, so they are d-block elements but are not regarded as transition metals.

• Option (1) Cu — Regarded as a transition metal. Cu (Z = 29) is [Ar]3d¹⁰4s¹, but its common ion \( \ce{Cu^{2+}} \) is [Ar]3d⁹, an incomplete d subshell.

• Option (2) Sc — Regarded as a transition metal. Sc (Z = 21) is [Ar]3d¹4s²; its 3d subshell is incomplete.

• Option (3) Mn — Regarded as a transition metal. Mn (Z = 25) is [Ar]3d⁵4s²; its 3d subshell is incomplete.

• Option (4) Zn — Not regarded as a transition metal. Zn (Z = 30) is [Ar]3d¹⁰4s²; losing the two 4s electrons gives its only common ion, \( \ce{Zn^{2+}} \): [Ar]3d¹⁰. The d subshell is full in both the atom and the ion.

NCERT (2026-27 edition):
The d- and f-Block Elements – …

Note: The same/similar question has been asked in different years by NTA as per the details given below: