There is a very little difference in acidic strengths of H3PO4, H3PO3 and H3PO2. — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Thallium (Tl) is a Group 13 element with a valence electronic configuration of 6s2 6p1. Step 2: Due to the inert pair effect, the 6s2 electron pair is strongly held by the nucleus and does not easily participate in bonding, making the +1 oxidation state exceptionally stable. Step 3: However, under highly oxidizing conditions, all three valence electrons can participate to show a +3 oxidation state. Thus, the possible oxidation states are +1 and +3, corresponding to option (d).