A coloured solution of an inorganic salt reacts with potassium thiocyanate to give first a black precipitate, which slowly turns white. The salt solution also gives black precipitate with `H_(2)S` gas in slightly acidic medium. The black precipitate dissolves in potassium cyanide forming a colourless solution. The basic radical present in the inorganic salt is:

Options

A. `Bi^(3+)`
B. `Cu^(2+)`
C. `Hg^(2+)`
D. none of these

Answer

B

Explanation