The pair of compounds which cannot exist together in aqueous solution is :<br>(I) NaH2PO4 and NaHCO3 — s Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Evaluate the reaction of each option with sodium hydroxide solution. Sulfur and Iodine undergo disproportionation reactions, while ammonium chloride reacts to release ammonia gas (NH3), which is not highly inflammable under normal conditions. Step 2: Zinc is an amphoteric metal and reacts with hot, concentrated sodium hydroxide solution to produce sodium zincate and release hydrogen gas: Zn + 2NaOH -> Na2ZnO2 + H2. Step 3: Because hydrogen gas is highly inflammable, Zinc is the reactant that yields an inflammable gas, corresponding to option (b).