The correct statements from the following are : (A) $\mathrm{Tl}^{3+}$ is a powerful oxidising agent (B) $\mathrm{Al}^{3+}$ does not get reduced easily (C) Both $\mathrm{Al}^{3+}$ and $\mathrm{Tl}^{3+}$ are very stable in solution (D) $\mathrm{Tl}^{+}$ is more stable than $\mathrm{Tl}^{3+}$ (E) $\mathrm{Al}^{3+}$ and $\mathrm{Tl}^{+}$ are highly stable Choose the correct answer from the options given below :

JEE Main · 2025 · 07 Apr 2025 · Shift 2 · p-Block Elements

The correct statements from the following are :
(A)

Tl^{3 +}

is a powerful oxidising agent
(B)

Al^{3 +}

does not get reduced easily
(C) Both

Al^{3 +}

and

Tl^{3 +}

are very stable in solution
(D)

Tl^{+}

is more stable than

Tl^{3 +}

(E)

Al^{3 +}

and

Tl^{+}

are highly stable

Choose the correct answer from the options given below :

(A)(A), (B), (C), (D) and (E)
(B)(A), (B), (D) and (E) only✓ Correct
(C)(B), (D) and (E) only
(D)(A), (C) and (D) only

Answer: (B)

Solution

Down group 13 the inert pair effect makes the lower oxidation state of the heavier element favourable, so for thallium the

+ 1

state is more stable than the

+ 3

state. Thallium(III) therefore tends to gain electrons and fall back to thallium(I), which makes it a powerful oxidising agent and also means it is not stable in solution. Aluminium shows no such effect: its

+ 3

state is strongly preferred and its very negative reduction potential shows it strongly resists reduction, so aluminium(III) is difficult to reduce and highly stable. Taken together, aluminium(III) and thallium(I) are the highly stable ions. The correct statements are that thallium(III) is a powerful oxidising agent, that aluminium(III) is not reduced easily, that thallium(I) is more stable than thallium(III), and that aluminium(III) and thallium(I) are highly stable.

JEE Main · 2025 · 07 Apr 2025 · Shift 2 · Single correct option

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JEE Main · 2025 · 07 Apr 2025 · Shift 2 · p-Block Elements

Solution

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