JEE Main 2026 — Apr 4, Shift 1 — Chemistry solution

JEE Main2026Apr 4, Shift 1Chemistry

The correct statements among the following are,

A. Mo(VI) and W(VI) are less stable than Cr(VI).

B. $C e^{4 +}$ and $T b^{4 +}$ are oxidant while $E u^{2 +}$ and $Y b^{2 +}$ 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 :

A
A and B Only
B
C and D Only
C
B and D Only
D
A and C Only

Solution

A. Down group $6$ , higher oxidation states become more stable, so Mo(VI) and W(VI) are more stable than Cr(VI). Incorrect.

B. For lanthanoids, the $+ 3$ state is the most stable. Hence $+ 4$ ions ( $C e^{4 +}, T b^{4 +}$ ) tend to gain an electron and act as oxidants, while $+ 2$ ions ( $E u^{2 +}, Y b^{2 +}$ ) tend to lose an electron and act as reductants. Correct.

C. Configurations: Cm is $[Rn] 5 f^{7} 6 d^{1} 7 s^{2}$ , giving $7 + 1 = 8$ unpaired electrons; Am is $[Rn] 5 f^{7} 7 s^{2}$ , giving $7$ unpaired electrons. So Cm does not have seven. Incorrect.

D. Actinoid contraction is greater per element than lanthanoid contraction because $5 f$ orbitals shield the nuclear charge less effectively than $4 f$ . Correct.

Hence only B and D are correct.

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