Chemistry · d and f Block Elements

JEE Main 2026 — 4 April, Morning Shift — Question 57

The correct statements among the following are,

A. $\mathrm{Mo}(\mathrm{VI})$ and $\mathrm{W}(\mathrm{VI})$ are less stable than $\mathrm{Cr}(\mathrm{VI})$ .

B. $\mathrm{Ce}^{4+}$ and $\mathrm{Tb}^{4+}$ are oxidant while $\mathrm{Eu}^{2+}$ and $\mathrm{Yb}^{2+}$ are reductant.

C. Cm and Am have seven unpaired electrons.

D. Actinoid contraction is greater from element to element than lanthanoid contraction.

Choose the correct answer from the options given below :

Option A:
A and B Only
Option B:
C and D Only
Option C:
B and D Only
Correct
Option D:
A and C Only

Answer: C

Step-by-step solution

(A) $\mathrm{Mo}(\mathrm{VI})$ & $\mathrm{W}(\mathrm{VI})$ more stable than $\mathrm{Cr}(\mathrm{VI})$ (B) In lanthanoids +3 oxidation state is more stable hance +4 ions act as oxidising agents and +2 ions act as reducing agents. (C) $\mathrm{Cm}-[\mathrm{Rn}] 5 \mathrm{f}^{7} 6 \mathrm{~d}^{1} 7 \mathrm{~S}^{2}=8$ unpaired electrons $\mathrm{Am}-[\mathrm{Rn}] 5 \mathrm{f}^{7} 6 \mathrm{~S}^{2}=7$ unpaired electrons (D) Actinoid contraction is more than lanthanoid contraction

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Exam: JEE Main 2026
Paper: 4 April, Morning Shift
Subject: Chemistry
Chapter: d and f Block Elements
Topic: Inner transition elements (f-Block elements)

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Answer: C

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