Which of the following order is incorrect ? — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Assess options (a), (b), and (c). Lewis basicity of hydrides decreases down Group 15 as size increases (a is correct). Bond dissociation energy of halogen acids decreases down the group (b is correct). Thermal stability of Group 16 hydrides decreases down the group as bond lengths increase (c is correct). Step 2: Now look at option (d). CH4, SiH4, GeH4, and SnH4 are all highly symmetrical tetrahedral molecules with regular sp3 hybridization and zero lone pairs. Step 3: Because there is no asymmetric repulsion, the bond angles in all four hydrides are exactly 109.5° (they are equal). Therefore, stating that bond angle decreases as CH4 > SiH4 > GeH4 > SnH4 is incorrect, matching option (d).