JEE Advanced · 2018 · 20 May 2018 · Paper 1 · p-Block Elements

(A) Basic character of oxides increases down the group. ${\mathrm{Bi}}_2{\mathrm{O}}_5$ is more basic than ${\mathrm{N}}_2{\mathrm{O}}_5$.

(B) According to Fajans' rules, smaller cation size leads to more covalent character. N³⁺ is smaller than Bi³⁺, so ${\mathrm{NF}}_3$ is more covalent than ${\mathrm{BiF}}_3$.

(C) ${\mathrm{NH}}_3$ exhibits hydrogen bonding, which significantly increases its boiling point. ${\mathrm{PH}}_3$ does not form hydrogen bonds, so it boils at a lower temperature.

(D) The N-N single bond is weaker than the P-P single bond due to high inter-electronic repulsion between lone pairs on adjacent nitrogen atoms.

Correct answers: (A), (B), and (C).