JEE Inorganic: Which Statements about Tl and Al are True? ✅

 

❓ Question

Which of the following statements are correct?

(A) Tl³⁺ is a powerful oxidising agent
(B) Al³⁺ does not get reduced easily
(C) Both Al³⁺ and Tl³⁺ are very stable in solution
(D) Tl⁺ is more stable than Tl³⁺
(E) Al³⁺ and Tl⁺ are highly stable

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🖼️ Question Image

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✍️ Short Solution

We evaluate each statement using periodic trends, standard reduction potentials, and the inert-pair effect.

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(A) Tl³⁺ is a powerful oxidising agent — True

• Thallium in +3 state is relatively unstable because of the inert-pair effect (the 6s electrons are reluctant to participate in bonding).

• Tl³⁺ tends to accept electrons to form the more stable Tl⁺ (6s²), so it oxidizes other species and itself gets reduced → hence Tl³⁺ acts as a strong oxidant in solution.

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(B) Al³⁺ does not get reduced easily — True

• Aluminium’s standard reduction potential (Al³⁺/Al) is strongly negative (≈ −1.66 V), meaning reduction to metallic Al is thermodynamically unfavorable in aqueous solution.

• The Al³⁺ ion is highly stabilized by hydration and strong ligand interactions, so it does not get reduced easily — statement B is correct.

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(C) Both Al³⁺ and Tl³⁺ are very stable in solution — False

• Al³⁺ is indeed quite stable in aqueous solution (common and strongly hydrated).

• Tl³⁺, however, is not very stable — it is a strong oxidant and readily reduces to Tl⁺.

• Therefore claiming both are very stable is incorrect.

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(D) Tl⁺ is more stable than Tl³⁺ — True

• Due to the inert-pair effect, the +1 oxidation state (Tl⁺, with a filled 6s² pair) is favored and more commonly encountered; Tl³⁺ is less stable and readily reduced.

• So Tl⁺ being more stable than Tl³⁺ is correct.

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(E) Al³⁺ and Tl⁺ are highly stable — True

• Al³⁺: stable because of high charge density, strong hydration and formation of complexes — common and persistent in solution.

• Tl⁺: stabilized by inert-pair effect; Tl(I) compounds are common and chemically robust.

• Thus both Al³⁺ and Tl⁺ are indeed highly stable in their respective contexts.

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🧮 Image Solution (Summary Table)

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✅ Conclusion & Final Answer

✅ Correct statements:

$$\boxed{{\displaystyle \text{(A), (B), (D), (E)}}}$$