JEE Advanced 2026 — Paper 1 — CHEM-II solution

JEE Advanced2026Paper 1CHEM-II

Correct statement(s) about the compounds $X$ , $Y$ and $Z$ is (are)

$MnO_{2} + conc. HCl ⟶ MnCl_{2} + X (greenish yellow gas) + H_{2} O$

$NH_{3} + X (excess) ⟶ Y +$ ...

$X + F_{2} (excess) 573 K Z$

A
$X$ is used for sterilizing drinking water.
B
$Y$ has a planar structure.
C
$Z$ is used in the enrichment of $^{235} U$ .
D
$Y$ is a stronger Lewis base than ammonia.

Solution

Identify the species. $X = Cl_{2}$ (greenish-yellow gas). $Y = NCl_{3}$ (from NH $_{3}$ + excess Cl $_{2}$ ). $Z = ClF_{3}$ (Cl $_{2}$ + excess F $_{2}$ at 573 K).

(A) Cl $_{2}$ is widely used to disinfect/sterilise drinking water. Correct.

(B) NCl $_{3}$ has an sp $^{3}$ N with one lone pair, giving a pyramidal (not planar) geometry. Incorrect.

(C) ClF $_{3}$ converts solid UF $_{4}$ to volatile UF $_{6}$ ( $U + 3 ClF_{3} \to UF_{6} + 3 ClF$ ), the volatile fluoride used in $^{235}$ U enrichment by gas diffusion / centrifugation. Correct.

(D) In NCl $_{3}$ , the three highly electronegative Cl atoms withdraw electron density from N by the inductive effect, reducing the availability of the nitrogen lone pair for donation. NCl $_{3}$ is therefore a weaker Lewis base than NH $_{3}$ , not stronger. Incorrect.

Correct answers: (A), (C).

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