Which of the following metal on burning in moist air does not give smell of ammonia ? — s Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: When highly reactive metals are burned in air, they can react with atmospheric nitrogen to form metal nitrides. Lithium (Li) and alkaline earth metals (Mg, Ca) easily form nitrides (Li3N, Mg3N2, Ca3N2) due to high lattice energy stabilization. Step 2: Potassium (K) has a larger cationic size and lower lattice energy, which prevents it from reacting directly with nitrogen gas to form a stable nitride on burning in air. Step 3: Upon exposure to moisture, the nitrides of Li, Mg, and Ca hydrolyze to release ammonia gas (NH3), which has a characteristic sharp smell. Since Potassium does not form a nitride, it does not produce ammonia under these conditions. Thus, option (c) is correct.