Reddish brown (chocolate) precipitate is formed by mixing solutions containing: — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Adding NH4Cl and NH4OH to CrCl3 precipitates chromium(III) as a green gelatinous hydroxide, Cr(OH)3 (compound A). Step 2: Reacting Cr(OH)3 with sodium peroxide (Na2O2) in water oxidizes the Cr(III) to Cr(VI), forming a yellow solution of sodium chromate, Na2CrO4 (compound B). Step 3: When lead acetate is added to the sodium chromate solution, it forms a bright yellow precipitate of lead chromate, PbCrO4 (compound C). Thus, option (d) is the correct answer.