JEE Main 2026 — Jan 28, Shift 1 — Chemistry solution

JEE Main2026Jan 28, Shift 1Chemistry

Given below are two statements:

Statement I: The number of pairs, from the following, in which both the ions are coloured in aqueous solution is 3.

$[Sc^{3 +}, Ti^{3 +}]$ , $[Mn^{2 +}, Cr^{2 +}]$ , $[Cu^{2 +}, Zn^{2 +}]$ and $[Ni^{2 +}, Ti^{4 +}]$

Statement II: Th $^{4 +}$ is the strongest reducing agent among Th $^{4 +}$ , Ce $^{4 +}$ , Gd $^{3 +}$ and Eu $^{2 +}$ .

In the light of the above statements, choose the correct answer from the options given below

A
Statement I is true but Statement II is false
B
Statement I is false but Statement II is true
C
Both Statement I and Statement II are false
D
Both Statement I and Statement II are true

Solution

Statement I: An aqueous ion is coloured when it has unpaired d-electrons enabling d-d transitions. Check each pair:

$[Sc^{3 +}, Ti^{3 +}]$ : Sc $^{3 +}$ is d $^{0}$ (colourless), Ti $^{3 +}$ is d $^{1}$ (coloured). Not both coloured.

$[Mn^{2 +}, Cr^{2 +}]$ : Mn $^{2 +}$ is d $^{5}$ (pale pink), Cr $^{2 +}$ is d $^{4}$ (blue). Both coloured.

$[Cu^{2 +}, Zn^{2 +}]$ : Cu $^{2 +}$ d $^{9}$ (blue), Zn $^{2 +}$ d $^{10}$ (colourless). Not both coloured.

$[Ni^{2 +}, Ti^{4 +}]$ : Ni $^{2 +}$ d $^{8}$ (green), Ti $^{4 +}$ d $^{0}$ (colourless). Not both coloured.

Only 1 pair has both ions coloured, not 3. False.

Statement II: Th $^{4 +}$ has no further accessible higher oxidation state (5f $^{0}$ , 6d $^{0}$ ) and cannot act as a reducing agent at all. Among the four, Eu $^{2 +}$ is the strongest reducing agent (it readily oxidises to Eu $^{3 +}$ ). False.

$∴$ Both statements are false. Option (3).

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