It is recommended that liquor ammonia bottle should be opened after cooling it in ice for sometime. — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: The thermal stability of Group 15 hydrides (MH3) is determined by the strength of the metal-hydrogen (M-H) bond. Step 2: Down the group, the atomic size of the central element (M) increases (N < P < As < Sb < Bi), which increases the M-H bond length and decreases the bond dissociation energy. Step 3: Consequently, the thermal stability decreases down the group in the order NH3 > PH3 > AsH3, matching option (a).