(i) A yellow precipiate of the compound A is formed on passing `H_(2)S` through a neutral solution of the salt B.
(ii) The compound A is soluble in hot dilute `HNO_(3)` but insoluble in yellow ammonium sulhpide.
(iii) The The solution of B, on treatment with a small quantitity of `NH_(3)`, gives a white precipitate soluble in an excess of the reagent, forming a compound C.
(iv). The solution of B gives a white precipitate with a small concentration of KCN. the precipitate is soluble in an excess of the reagent, forming a compound D.
(v) the solution of D, on treatment with `H_(2)S`, gives A.
(vi) The solution of B in dilute HCl, on treatment with a solution of `BaCl_(2)`, gives a white precipitate of the compound E, which is almost insoluble in concentrated `HNO_(3)`.
Q. Which of the following are the white precipitate and the soluble substance formed by the excess of the KCN reagent. respectively, in (iv) ?

Options

A. `As(CN)_(3) and [As(CN)_(6)]^(2-)`
B. `Sn(CN)_(3) and [Sb(CN)_(6)]^(3-)`
C. `Zn(CN)_(2) and [Zn(CN)_(4)]^(2-)`
D. `Cd(CN)_(2) and [Cd(CN)_(4)]^(2-)`

Answer

D