Which of the following compounds are coloured? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Identify compound Y. Y is a gas that reacts with HCl to produce dense white fumes (NH4Cl) and forms a brown precipitate with Nessler's reagent, identifying it as ammonia (NH3). Step 2: Identify compound Z. Z is a gas that reacts with NH3 to form white fumes and precipitates Ag+, Pb2+, and Hg+ as white chlorides from aqueous solutions, identifying it as hydrogen chloride (HCl). Step 3: Reconstruct solid 'X'. Thermal decomposition of 'X' yields equimolar NH3 and HCl. Therefore, solid 'X' is ammonium chloride (NH4Cl), matching option (a).