Q23 · CSIR-NET Chemistry, June 2012

Paper: CSIR-NET June 2012 · Subject: Inorganic Chemistry · Chapter: Acids and Bases · Topic: Acids & Bases – General · Marks: 2 · Difficulty: Medium

In the reactions (A) and (B),
\[ \begin{array}{l} n(\mathrm{H_2O}) + \mathrm{Cl^{-}} \rightarrow [\mathrm{Cl(H_2O)_n}]^{-} \quad\text{(A)} \\ (\mathrm{H_2O})_6 + \mathrm{Mg^{2+}} \rightarrow [\mathrm{Mg(H_2O)_6}]^{2+} \quad\text{(B)} \end{array} \]
Water behaves as
(a)An acid in both (A) and (B)
(b)An acid in (A) and a base in (B)
(c)A base in (A) an acid in (B)
(d)A base in both (A) and (B)
Answer
Answer: B ✓ checked by 4AB · confidence high

The source book printed C; on checking, B is correct — see the explanation.

Printed C; the roles are the other way round.

Explanation
In (A) water solvates Cl⁻ through its H atoms — accepting electron density, a Lewis acid. In (B) water donates its O lone pair to Mg²⁺ — a Lewis base. Acid in (A), base in (B).

Study loop for Acids and Bases

1. Practise the PYQsPrevious-year questions, with answers

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