JEE Main 2025 Jan 23 Shift 2, Chemistry Q6: d-Block Elements

JEE Main2025Jan 23, Shift 2Chemistry

Identify A, B and C in the given below reaction sequence

A
PbCl $_{2}$ , PbSO $_{4}$ , PbCrO $_{4}$
B
PbS, PbSO $_{4}$ , PbCrO $_{4}$
C
PbS, PbSO $_{4}$ , Pb(CH $_{3}$ COO) $_{2}$
D
PbCl $_{2}$ , Pb(SO $_{4}$ ) $_{2}$ , PbCrO $_{4}$

Solution

The key is to identify A, B, C from the lead chemistry that is implied.

A $\to$ Pb(NO $_{3}$ ) $_{2}$ with HNO $_{3}$ : dilute nitric acid converts lead sulfide to soluble lead nitrate, so A $=$ PbS.

Pb(NO $_{3}$ ) $_{2}$ $\to$ B with H $_{2}$ SO $_{4}$ : sulfate ion precipitates the insoluble white salt PbSO $_{4}$ . So B $=$ PbSO $_{4}$ .

B $\to$ C: ammonium acetate/acetic acid solubilises PbSO $_{4}$ as a soluble lead-acetate complex; adding K $_{2}$ CrO $_{4}$ then precipitates the bright yellow PbCrO $_{4}$ . So C $=$ PbCrO $_{4}$ .

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JEE Main 2025 Jan 23 Shift 2, Chemistry Q6: d-Block Elements

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