JEE Advanced 2024 Paper 2 · Chemistry · s-Block, p-Block Elements and Hydrogen · medium

(s) about the compounds of phosphorus, sulphur, nitrogen and xenon.

One or more options correct

Choose the correct statement(s) about the compounds of phosphorus, sulphur, nitrogen and xenon.

A. $\mathrm{H_3PO_2}$ is a monobasic acid and acts as a reducing agent, being oxidised to $\mathrm{H_3PO_3}$ or $\mathrm{H_3PO_4}$
B. On heating, $\mathrm{(NH_4)_2Cr_2O_7}$ gives a green solid residue together with $\mathrm{N_2(g)}$
C. $\mathrm{SO_2}$ decolourises acidified $\mathrm{KMnO_4}$ by acting as an oxidising agent
D. $\mathrm{XeO_3}$ is pyramidal and $\mathrm{XeOF_4}$ is square pyramidal, and in each of them Xe carries one lone pair

Show answer and solution

Answer: A, B, D

(A) Correct. In

\mathrm{H_3PO_2}

only the one P–OH hydrogen is ionisable (two P–H bonds), so it is monobasic, and the P–H bonds make it a strong reducing agent (it reduces

\mathrm{Ag^+}

to Ag). (B) Correct.

\mathrm{(NH_4)_2Cr_2O_7\xrightarrow{\Delta}N_2+Cr_2O_3+4H_2O}

;

\mathrm{Cr_2O_3}

is green. (C) Incorrect.

\mathrm{SO_2}

is oxidised to sulphate by

\mathrm{MnO_4^-}

, so it acts as a reducing agent, and the purple colour disappears as

\mathrm{Mn^{2+}}

forms. (D) Correct.

\mathrm{XeO_3}

: three bond pairs and one lone pair,

sp^3

, trigonal pyramidal;

\mathrm{XeOF_4}

: five bond pairs and one lone pair,

sp^3d^2

, square pyramidal. Answer: A, B and D.

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