With reference to transition metals which of the following statements are correct?
A. Electronic configuration is represented by \((n - 1)d^{1-10}ns^{1-2}\)
B. They exhibit catalytic property
C. Some of them form interstitial compounds
D. In \(Ni(CO)_4\) and \(Fe(CO)_5\), the oxidation state of \(Ni\) and \(Fe\) are \(+4\) and \(+5\) respectively.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, B, C only
(A) Configuration (n−1)d1–10ns1–2 — True. This is the general outer configuration of the d-block elements (Pd, 4d105s0, is the one exception).
(B) They exhibit catalytic property — True. Their variable oxidation states and ability to form complexes make them good catalysts (\( \ce{V2O5} \) in the Contact process, Fe in the Haber process, Ni in hydrogenation).
(C) Some of them form interstitial compounds — True. Small atoms such as H, C or N are trapped in the crystal lattices of metals (TiC, \( \ce{Mn4N} \), \( \ce{Fe3H} \)).
(D) Oxidation states of Ni in Ni(CO)4 and Fe in Fe(CO)5 are +4 and +5 — False. CO is a neutral ligand, so x + 4(0) = 0 and x + 5(0) = 0: both metals are in the zero oxidation state.
NCERT (2026-27 edition):
Electronic Configurations of the d-Block Elements – …
