Question

Statement-1 :`Cu^(2+)` and `Cd^(2+)` ions form complexes with excess of potassium cyanide solution.
Statement-2 : On passing `H_(2)S` gas, complex `[Cu(CN)_(4)]^(3-)` is not effected but `[Cd(CN)_(4)]^(2-)` gives yellow precipitated.
A. STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is correct explanation for STATEMENT-1
B. STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is not correct explanation for STATEMENT-2
C. STATEMENT-1 is true, STATEMENT-2 is false
D. STATEMENT-1 is false, STATEMENT-2 is true

Answer 1

Correct Answer - B
Statement-1 :`Cu^(2+) +6CN^(-) to [Cu(CN)_(4)]^(3-) + (CN)_(2) , Cd^(2+) + 4CN^(-) to [Cd(CN)_(4)]^(2-)`
Statement-2 :`[Cu(CN)_(4)]^(3-)` being stable complex is not effected by `H_(2)S` gas but `[Cd(CN)_(4)]^(2-)` is not so stable and gives yellow precipitate with `H_(2)S`.
`[Cd(CN)_(4)]^(2-)+H_(2)S to CdS darr ("yellow")+2H^(+) + 4CN^(-)`