Chemistry - Salt Analysis Question with Solution | TestHub

ChemistrySalt AnalysisTEST OF CATIONS Dry Test, Group Analysis, Group 1,2Medium2 minQB

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Passage / Comprehension

"M" is a silver-white metal. It dissolves slowly in dilute acid with the evolution of H₂ and produces an aqueous, colorless solution of metal ion (X).

$(X)$ produce ppt with excess NaOH but produce colourless solution with excess of $NH_{3}$ . Yellow ppt obtain by reaction of $(X)$ with $H_{2} S$ is not soluble in ammonium polysulphide.

Select correct for mixture of $(X)_{(Aq .)} + CuSO_{4 (Aq .)}$ :-

Options:

Answer:

Solution:

Metal M is Zn, so X = Zn²⁺ (amphoteric cation).
In the mixture with CuSO₄, we need a reagent that specifically detects Cu²⁺.
KI reacts with Cu²⁺ to form white precipitate of CuI (Cu²⁺ → Cu⁺ reduction), while Zn²⁺ does not interfere.
Other reagents (NH₄OH, NaCN, K₄[Fe(CN)₆]) are not selective in presence of Zn²⁺.
Hence, correct option is D.

Stream:JEESubject:ChemistryTopic:Salt AnalysisSubtopic:TEST OF CATIONS Dry Test, Group Analysis, Group 1,2

⏱ 2mℹ️ Source: QB

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