JEE Main · 2021 · 22 Jul 2021 · Shift 2 · d and f Block Elements

The set having ions which are coloured and paramagnetic both is:

(A) $Ni^{2 +}, Mn^{7 +}, Hg^{2 +}$
(B) $Cu^{+}, Zn^{2 +}, Mn^{4 +}$
(C) $Sc^{3 +}, V^{5 +}, Ti^{4}$
(D) $Cu^{2 +}, Cr^{3 +}, Sc^{+}$ ✓ Correct

Answer: (D)

Solution

Colour from d-d transitions and paramagnetism both need a partly filled d subshell.

C u^{2 +}

3 d^{9}

and

C r^{3 +}

3 d^{3}

, each with unpaired d electrons, and

S c^{+}

has the configuration

[Ar] 3 d^{1} 4 s^{1}

, which also leaves electrons unpaired, so every ion of this set is coloured and paramagnetic. Each of the other sets contains at least one ion with an empty or a completely filled d subshell:

H g^{2 +}

Z n^{2 +}

and

C u^{+}

are

d^{10}

, while

M n^{7 +}

S c^{3 +}

V^{5 +}

and

T i^{4 +}

are

d^{0}

, and such ions are colourless and diamagnetic. The set that is both coloured and paramagnetic is

C u^{2 +}

C r^{3 +}

S c^{+}

JEE Main · 2021 · 22 Jul 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 22 Jul 2021 · Shift 2 · d and f Block Elements

Solution

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