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Solution 'A' gives a white sulphide precipitate with group IV reagent. Its precipitate dissolves in dil.HCl to give solution 'B'. A bluish white precipitate appears when potassium ferrocyanide (K4Fe(CN)6) solution is added to the solution 'B' after neutralisation by NH4OH solution. The cation present in solution 'A' is

A
Mn2+
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B
Zn2+
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C
Ni2+
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D
Co2+
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Solution

The correct option is B Zn2+
Group IV cations forms sulphide precipitate with H2S which is the group IV reagent.

Confirmation of Mn2+:
Zinc sulphide dissolves in hydrochloric acid to form zinc chloride.
(a). When potassium ferrocyanide K4Fe(CN)6 solution is added to the solution after neutralisation by NH4OH solution, a white or a bluish white precipitate
of zinc ferrocyanide appears.
2ZnCl2+K4[Fe(CN)6]Zn2[Fe(CN)6]Zinc ferrocyanide+4KCl

(b). On addition of sodium hydroxide solution to zinc chloride, it gives a white precipitate of zinc hydroxide, which is soluble in excess of NaOH solution on heating.
This confirms the presence of Zn2+ ions.
ZnCl2+2NaOHZn(OH)2+2NaCl
Zn(OH)2+2NaOHNa2ZnO2Sodium zincate+2H2O

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