An aqueous solution contains a mixture of Fe ³⁺ and Mn ²⁺ ions. To this solution, solid NH ₄ Cl is added followed by an excess of NH ₄ OH , resulting in the formation of Precipitate A. The mixture is filtered, and H ₂ S gas is passed through the filtrate, which leads to the formation of Precipitate B. The colors of Precipitate A and Precipitate B, respectively, are:

Step-by-step solution

The separation of cations in qualitative analysis is based on the sequential use of group reagents. The addition of NH ₄ OH in the presence of NH ₄ Cl is the group reagent for Group III cations. In the given mixture, Fe ³⁺ belongs to Group III and precipitates as iron(III) hydroxide, Fe(OH) ₃ . This precipitate has a characteristic reddish-brown color, which identifies Precipitate A. The filtrate contains the Mn ²⁺ ions, which belong to Group IV. When H ₂ S gas is passed through this alkaline filtrate, manganese(II