A chloride salt solution acidified with dil.HNO₃ gives a curdy white precipitate, [A], on addition of AgNO₃. [A] on treatment with NH₄OH gives a clear solution B. A and B are respectively :

Solution

Chemistry ma’am · 3 steps

Silver chloride is the white curd, and ammonia pulls Ag⁺ into a soluble diammine complex.

1. Precipitate A. Chloride ions meet silver ions and form insoluble silver chloride: Cl⁻ + Ag⁺ → AgCl v. The dilute HNO₃ only removes ions like CO₃²⁻ that would otherwise also precipitate with Ag⁺, so A is plain AgCl.
2. Dissolving in ammonia. NH₃ is a good ligand for Ag⁺. It forms the linear complex ion [Ag(NH₃)₂]⁺, which is soluble, so the white curd dissolves to a clear solution.

   AgCl + 2NH₄OH → [Ag(NH₃)₂]Cl + 2H₂O

3. So. A is AgCl and B is diamminesilver(I) chloride, [Ag(NH₃)₂]Cl, which is option (b).

The idea to keep. In NH₄OH, Ag⁺ binds to NH₃, not to OH⁻. That is why AgCl dissolves in ammonia as [Ag(NH₃)₂]⁺, and this confirms chloride.

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