JEE Advanced · Chemistry · 31. Practical Chemistry

The reagent(s) that can selectively precipitate $S^{2 -}$ from a mixture of $S^{2 -}$ and $S O_{4}^{2 -}$ in aqueous solution is (are)

A $C u C l_{2}$
B $B a C l_{2}$
C $P b {(O O C C H_{3})}_{2}$
D $N a_{2} [F e {(C N)}_{5} N O]$

Verified Solution

Answer & Solution

Correct Answer

(C) $P b {(O O C C H_{3})}_{2}$

Step-by-step Solution

Detailed explanation

(A)

(B)

(C)

(D)

Note:
$\left.\begin{array}{c} PbSO _4 Ksp =2.5 \times 10^{-8} \\ PbS Ksp =3 \times 10^{-28}\end{array}\right\}$ Which are not given in question
As in question selective precipitation is asked

P b S

will be precipitate much easier than

P b S O_{4}

though both are insoluble. Hence, answer should be

P b {(O O C - C H_{3})}_{2}

also along with

C u C l_{2}

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

LIST-

I

contains metal species and LIST-

II

contains their properties.

List - I	List - II
(I) $\left[ Cr ( CN )_6\right]^{4-}$	(P) $t _{2 g}$ orbitals contain 4 electrons
(II) $\left[ RuCl _6\right]^{2-}$	(Q) $\mu$ spin - only $=4.9$ BM
(III) $\left[ Cr \left( H _2 O \right)_6\right]^{2+}$	(R) low spin complex ion
(IV) $\left[ Fe \left( H _2 O \right)_6\right]^{2+}$	(S) metal ion in 4 + oxidation state
	(T) $d ^4$ species

[Given: Atomic number of

Cr = 24, Ru = 44, Fe = 26

]
Match each metal species in LIST-

I

with their properties in LIST-

II

, and choose the correct option

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List - I	List - II
(I) \(\left[ Cr ( CN )_6\right]^{4-}\)	(P) \(t _{2 g}\) orbitals contain 4 electrons
(II) \(\left[ RuCl _6\right]^{2-}\)	(Q) \(\mu\) spin - only \(=4.9\) BM
(III) \(\left[ Cr \left( H _2 O \right)_6\right]^{2+}\)	(R) low spin complex ion
(IV) \(\left[ Fe \left( H _2 O \right)_6\right]^{2+}\)	(S) metal ion in 4 + oxidation state
	(T) \(d ^4\) species

List - I	List - II
(P)	1. Inversion of configuration
(Q)	2. Retention of configuration
(R)	3. Mixture of enantiomers
(S)	4. Mixture of structural isomers
	5. Mixture of diastereomers

The reagent(s) that can selectively precipitate S2- from a mixture of S2- and SO42- in aqueous solution is (are)

Step-by-step Solution

The reagent(s) that can selectively precipitate $S^{2 -}$ from a mixture of $S^{2 -}$ and $S O_{4}^{2 -}$ in aqueous solution is (are)