Three black powder A,B,D are kept in three dishes. A dissolves in dil `H_(2)SO_(4)` to give blue solution. Moistened with HCl, A gives a green colour in flame test. B does not dissolve in dil HCl but when boiled with concentrated HCl, dissolves giving chlorine. This solution with`H_(2)S` in ammonical solution produces a flesh coloured precipitate C does not dissolve in HCl but when heated with `KNO_(3)`, burns away evolving a gas which lime water milky. What are A,B, & C ?

Explanation

`A: CuO overset(H_(2)SO_(4))(rarr)CuSO_(4)("blue")overset("Flame test")(rarr)` green colour
`B:MnO_(2)overset("conc."HCl)(rarr) MnCl_(2)+Cl_(2)underset(NH_(4)^(+))overset(H_(2)S)(rarr)MnS` (flesh colour)
`C:` Carbon powder `C overset(KNO_(3))(rarr)CO_(2)overset("Lime water")(rarr)`milky