The second electron gain enthalpies (in kJ mol-1) of oxygen and sulphur respectively are : — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Determine the identity and valency of elements P and Q based on their period and group. P (Period 2, Group 15) is Nitrogen, which has a valency of 3. Q (Period 3, Group 2) is Magnesium, which has a valency of 2. Step 2: To form a neutral compound, the positive and negative valencies must balance: three divalent atoms of Q combine with two trivalent atoms of P, forming Q3P2 (or written as P2Q3 in the options). Step 3: Therefore, the formula of the compound is P2Q3, matching option (c).