How many of the following elements are NOT regarded as transition ele…

The correct answer is Option (1) → 4

According to IUPAC, a transition metal has an incomplete d subshell either in the neutral atom or in its ions. A d-block element whose d subshell is full (d¹⁰) both in the ground state and in its common oxidation state is not regarded as a transition element.

Not regarded as transition elements:

• Zn (3d¹⁰ 4s²; Zn²⁺ is 3d¹⁰)

• Cd (4d¹⁰ 5s²; full 4d subshell in the atom and in Cd²⁺)

• Hg (5d¹⁰ 6s²)

• Cn (6d¹⁰ 7s², the (n−1)d¹⁰ns² configuration of Zn, Cd and Hg)

Transition elements:

• Sc — 3d¹ 4s²: the 3d subshell is incomplete in the ground state.

• Cu — the atom is 3d¹⁰ 4s¹, but the common Cu²⁺ ion is 3d⁹.

• Ag — the atom is 4d¹⁰ 5s¹, but in the +2 state the 4d subshell is incomplete (4d⁹).

• Ni — 3d⁸ 4s²: the 3d subshell is incomplete in the ground state.

Not regarded as transition elements: Zn, Cd, Hg and Cn = 4.

NCERT (2026-27 edition):
The d- and f-Block Elements – “…Now according to IUPAC, transition metals are defined as metals which have incomplete d subshell either in neutral atom or in their ions.”

4.2 Electronic Configurations of the d-Block Elements – “The electronic configurations of outer orbitals of Zn, Cd, Hg and Cn are represented by the general formula (n-1)d¹⁰ns². The orbitals in these elements are completely filled in the ground state as well as in their common oxidation states. Therefore, they are not regarded as transition elements.”

Answers to Some Intext Questions – “4.1 Silver (Z = 47) can exhibit +2 oxidation state wherein it will have incompletely filled d-orbitals (4d), hence a transition element.”