The solubility of AgCl will be maximum in which of the following?

Solution

Chemistry ma’am · 3 steps

Look for a common ion: any Ag⁺ or Cl⁻ already in solution pushes AgCl back out.

1. The equilibrium. AgCl dissolves as AgCl(s) ⇌ Ag⁺ (aq) + Cl⁻ (aq), with Kₛₚ = [Ag⁺][Cl⁻]. At a fixed temperature this product cannot exceed Kₛₚ.
2. Common ion effect. If the solvent already contains Ag⁺ or Cl⁻, much less AgCl can dissolve before the product reaches Kₛₚ. Le Chatelier's principle shifts the equilibrium to the left.

   Solvent	Common ion present	Solubility of AgCl (with Kₛₚ ≈ 1.8 × 10⁻¹⁰)
   0.01 M KCl	Cl⁻, 0.01 M	(1.8 × 10⁻¹⁰)/0.01 = 1.8 × 10⁻⁸ M
   0.01 M HCl	Cl⁻, 0.01 M	1.8 × 10⁻⁸ M
   0.01 M AgNO₃	Ag⁺, 0.01 M	1.8 × 10⁻⁸ M
   Deionised water	none	√(1.8 × 10⁻¹⁰) = 1.34 × 10⁻⁵ M

3. So. Only deionised water has no common ion, so AgCl is about 700 times more soluble there than in the other three. The answer is (d).

The idea to keep. Before you think about anything else, check whether the solvent shares an ion with the salt. A shared ion always lowers the solubility of a sparingly soluble salt.

Answer from the NTA final answer key. Solution by PrepWiser.