A coloured solution known to contain two metal ions, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper a

Question

A coloured solution known to contain two metal ions, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Dropwise addition of hydrochloric acid to the filtrate produced a white ppt. which dissolved in excess acid. Treatment of the residue on filter paper with a solution of strong oxidiser produced a reddish-violet solution. Indicate any pairs of ions:

Prashant Kotian · Accepted Answer

Correct answer: A. Zn2+ forms soluble [Zn(OH)4]2- (filtrate) which gives Zn(OH)2 ppt with HCl, dissolving in excess. Mn2+ forms Mn(OH)2 (white solid) which oxidizes to brown MnO(OH)2, and further to purple MnO4- with strong oxidizer.

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