When a brown compound of manganese (A) is treated with HCl it gives a gas (B). The gas taken in excess, reacts with `NH_(3)` to give an explosive compound (C ). Identify compound A, B and C.

Explanation

`underset((A))(MnO_(2))+4HClrarrMnCl_(2)+underset((B))(Cl_(2))+2H_(2)O`
`underset((B))(NH_(3))+underset("excess")(3Cl_(2))rarrunderset("(C)")(NCl_(3))+3HCl`