(P) -Δ-> (Q) metallic solid + (R)↑ + (S)↑; (X) -Δ-> (Y) amphoteric + (R)↑ + (S)↑. P & X are respecti — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Identify starting materials: Ferrous sulfide (FeS↓) is an insoluble black precipitate. Step 2: Observe reaction with dilute HCl: The hydrochloric acid protonates the sulfide ion to form hydrogen sulfide gas (H2S↑), which escapes, shifting the solubility equilibrium to dissolve the FeS. Step 3: Since the insoluble precipitate is converted into soluble FeCl2 and dissolved, this is a precipitate dissolution reaction (type B).