Cations present in slightly acidic solution are Al^3+, Zn^2+ and Cu^2+. The reagent which when added in excess to this solution would identity and separate Cu^2+ in one step is :

Question

Prashant Kotian · Accepted Answer

Correct answer: C. Step 1: When NaOH is added to the mixture containing Al3+, Zn2+, and Cu2+, all of them initially form hydroxide precipitates. Step 2: Since Al(OH)3 and Zn(OH)2 are amphoteric, they dissolve in excess NaOH to form soluble aluminate ([Al(OH)4]-) and zincate ([Zn(OH)4]2-) complexes. Step 3: In contrast, Cu(OH)2 is a basic hydroxide and remains insoluble as a characteristic blue precipitate, allowing both the identification and separation of Cu2+ in one step, matching option (c).

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