In the following reaction sequence in aqueous solution, the species $\mathbf{X}, \mathbf{Y}$ and $\mathbf{Z}$, respectively, are

(A) $\left[\mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}\right]^{3-}, \mathrm{Ag}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}, \mathrm{Ag}_{2} \mathrm{~S}$

(B) $\left[\mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{3}\right]^{5-}, \mathrm{Ag}_{2} \mathrm{SO}_{3}, \mathrm{Ag}_{2} \mathrm{~S}$

(C) $\left[\mathrm{Ag}\left(\mathrm{SO}_{3}\right)_{2}\right]^{3-}, \mathrm{Ag}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}, \mathrm{Ag}$

(D) $\left[\mathrm{Ag}\left(\mathrm{SO}_{3}\right)_{3}\right]^{3-}, \mathrm{Ag}_{2} \mathrm{SO}_{4}, \mathrm{Ag}$

JEE Advanced · 2016 · 22 May 2016 · Paper 2 · Coordination Compounds

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In the following reaction sequence in aqueous solution, the species

X, Y

and

Z

, respectively, are

(A) $[Ag (S_{2} O_{3})_{2}]^{3 -}, Ag_{2} S_{2} O_{3}, Ag_{2} S$ ✓ Correct
(B) $[Ag (S_{2} O_{3})_{3}]^{5 -}, Ag_{2} SO_{3}, Ag_{2} S$
(C) $[Ag (SO_{3})_{2}]^{3 -}, Ag_{2} S_{2} O_{3}, Ag$
(D) $[Ag (SO_{3})_{3}]^{3 -}, Ag_{2} SO_{4}, Ag$

Answer: (A)

Solution

Thiosulfate ion reacts with silver ion to form a soluble complex:

Ag^{+} + 2 S_{2} O_{3}^{2 -} ⟶ [Ag (S_{2} O_{3})_{2}]^{3 -}

This is

X

(clear solution). Excess

Ag^{+}

precipitates white

Ag_{2} S_{2} O_{3}

(

Y

). With time, hydrolysis occurs:

Ag_{2} S_{2} O_{3} + H_{2} O ⟶ Ag_{2} S + H_{2} SO_{4}

forming black

Ag_{2} S

(

Z

JEE Advanced · 2016 · 22 May 2016 · Paper 2 · Single correct option

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JEE Advanced · 2016 · 22 May 2016 · Paper 2 · Coordination Compounds

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