An queous solution of a substance gives a white precipitate on treating with dilute hydrochloric acid which dissolves on heating. When hydrogen sulphide is passed through the hot solution, a black precipitate is obtained. The substance is :

Options

A. `Hg_(2)^(2+)` salt
B. `Cr^(+)` salt
C. `Ag^(o+)` salt
D. `Pb^(2+)`salt

Answer

d

Explanation

A white precipitate which is soluble in hot water is lead chloride
`Pb^(2+) + 2HCI rarr underset(white)(PbCI_(2) darr ) + 2H^(oplus)`
`underset(Hot solution)(PbCI_(2))+H_(2)S overset(H^(o+))rarr overset(White)underset(Black)(PbSdarr) +2HCI`