A mixture of chlorides of Cu, Cd, Cr and Fe was dissolved in water acidified with dil. HCl and H 2 S gas was passed. It was filtered, and boiled later adding two drops of HNO 3 . To this solution

Question

A mixture of chlorides of Cu, Cd, Cr and Fe was dissolved in water acidified with dil. HCl and H 2 ​ S gas was passed. It was filtered, and boiled later adding two drops of HNO 3 ​ . To this solution NH 4 ​ Cl and NaOH were added in excess and filtered. The filtrate shall give test for :-

TestHub · Accepted Answer

Passing H₂S in acidic medium precipitates Group II sulfides like CuS and CdS, which are removed by filtration.

The filtrate contains Cr³⁺, Fe³⁺ and Na⁺ ions.

On adding excess NH₄Cl and NaOH, Fe(OH)₃ precipitates while chromium forms soluble NaCrO₂ complex in excess alkali.

Thus, the filtrate gives the test for Na⁺ and Cr³⁺.

Correct Answer: (C) Sodium and chromium ion

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