JEE Advanced · Chemistry · 8. Ionic Equilibrium

An acidified solution of $0.05 M {Zn}^{2 +}$ is saturated with $0.1 M H_{2} S$ . What is the minimum molar concentration $(M)$ of $H^{+}$ required to prevent the precipitation of $ZnS$ ? Use $K_{sp} (ZnS) = 1.25 \times 10^{- 22}$ and overall dissociation constant of $H_{2} S, K_{NET} = K_{1} K_{2} = 1 \times 10^{- 21}$

A 0.4
B 0.2
C 0.36
D 0.45

Verified Solution

Answer & Solution

Correct Answer

(B) 0.2

Step-by-step Solution

Detailed explanation

For

ZnS

K_{sp} (ZnS) = [{Zn}^{2 +}] \times [S^{2 -}] = 1.25 \times 10^{- 22}

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

Match the complexes in Column I with their properties listed in Column II. Indicate your answer by darkening the appropriate bubbles of the $4 \times 4$ matrix given in the ORS.

Column I	Column II
A. $\text O _2^{-} \longrightarrow \text{O} _2$ $+~\text O _2^{2-}$	P. Redox reaction
B. $\text{CrO} _4^{2-}+\text H ^{+} \longrightarrow$	Q. One of the products has trigonal planar structure
C. $\text{MnO} _4^{-}+ \text{NO} _2^{-}$ $+~ \text H ^{+} \longrightarrow$	R. Dimeric bridged tetrahedral metal ion
D. $\text{NO} _3^{-}+ \text H _2 \text{SO} _4$ $+~ \text{Fe} ^{2+} \longrightarrow$	S. Disproportionation

JEE Advanced 2007 Hard

Dissolving $1.24 g$ of white phosphorous in boiling $NaOH$ solution in an inert atmosphere gives a gas $Q$ . The amount of ${CuSO}_{4}$ (in $g$ ) required to completely consume the gas $Q$ is____
[Given: Atomic mass of
$\text H =1,\text O =16, \text{Na} =23,\text P =31,\text S=32,$ $\text{Cu} =63]$

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Column I	Column II
A. \(\text O _2^{-} \longrightarrow \text{O} _2\) \(+~\text O _2^{2-}\)	P. Redox reaction
B. \(\text{CrO} _4^{2-}+\text H ^{+} \longrightarrow\)	Q. One of the products has trigonal planar structure
C. \(\text{MnO} _4^{-}+ \text{NO} _2^{-}\) \(+~ \text H ^{+} \longrightarrow\)	R. Dimeric bridged tetrahedral metal ion
D. \(\text{NO} _3^{-}+ \text H _2 \text{SO} _4\) \(+~ \text{Fe} ^{2+} \longrightarrow\)	S. Disproportionation

An acidified solution of 0.05 M Zn2+ is saturated with 0.1 M H2S. What is the minimum molar concentration (M) of H+ required to prevent the precipitation of ZnS? Use Ksp(ZnS)=1.25×10-22 and overall dissociation constant of H2S, KNET=K1K2=1×10-21

Step-by-step Solution