Consider the following statements about the d-block elements.
(A) Palladium does not follow the general outer configuration (n−1)d1–10ns1–2; its configuration is 4d105s0.
(B) Chromium has the configuration 3d44s2 instead of 3d54s1.
(C) Zinc, cadmium, mercury and copernicium, with the outer configuration (n−1)d10ns2, are not regarded as transition elements.
(D) The d orbitals of the transition elements protrude to the periphery of an atom less than the s and p orbitals.
Which of the statements given above are correct? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A) and (C) only
The general outer configuration of the d-block elements is (n−1)d1–10ns1–2. There are exceptions, because the (n−1)d and ns orbitals differ very little in energy and half-filled and completely filled sets of orbitals are extra stable.
(A) Palladium does not follow the general outer configuration (n−1)d1–10ns1–2; its configuration is 4d105s0. — True. Pd has no 5s electron; all ten outer electrons are in the 4d orbitals.
(B) Chromium has the configuration 3d44s2 instead of 3d54s1. — False. It is the other way round: Cr is 3d54s1, with a half-filled 3d set, not 3d44s2.
(C) Zinc, cadmium, mercury and copernicium, with the outer configuration (n−1)d10ns2, are not regarded as transition elements. — True. Their d orbitals are completely filled in the ground state and in their common oxidation states.
(D) The d orbitals of the transition elements protrude to the periphery of an atom less than the s and p orbitals. — False. The d orbitals protrude more than the s and p orbitals, so they are more influenced by the surroundings and affect the atoms or molecules around them.
NCERT (2026-27 edition):
4.2 Electronic Configurations of the d-Block Elements – “In general the electronic configuration of outer orbitals of these elements is (n-1)d1–10ns1–2 except for Pd where its electronic configuration is 4d105s0.”
“…For example, consider the case of Cr, which has 3d5 4s1 configuration instead of 3d44s2; the energy gap between the two sets (3d and 4s) of orbitals is small enough to prevent electron entering the 3d orbitals.”
“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.”
“The d orbitals of the transition elements protrude to the periphery of an atom more than the other orbitals (i.e., s and p), hence, they are more influenced by the surroundings as well as affect the atoms or molecules surrounding them.”