Which combination gives maximum number of products ? — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Mercuric sulfide (HgS↓) is exceptionally insoluble, having an extremely low solubility product (Ksp). Step 2: Concentrated nitric acid (HNO3) alone, despite being a strong oxidizing acid, is unable to dissolve HgS (only aqua-regia can dissolve it by combining oxidation and coordination). Step 3: Since no dissolution or reaction takes place, this is classified as no reaction (type D), matching option (d).