A solution of a salt gives a precipitate on treatment with dilute HCl. The precipitate formed is filtered off and treated with `NH_(3)` whereby it turns black. The cation present in the salt is

Options

A. `Ag^(+)`
B. `Hg^(2+)`
C. `Hg_(2)^(2+)` and `Cd^(2+)`
D. `Pb^(2+)`

Answer

C

Explanation

`Hg_(2)^(2+)+HClrarrunderset(darr NH_(3))(Hg_(2)Cl_(2)darr)("white ppt")`
`Hg^(-)("Black")+Hg(NH_(2))Cl`