Question

A balck powder when heated with Conc. HCI gives a greenish yellow. Gas. The gas as an oxidising and bleaching agent. When it is passed over slake lime, a white poweder is formed which is a ready source of gas. The back powder and white powder respectively are
A. `KClO_3` and `NaClO_3`
B. `MnO_2` and `Ca(O Cl)_2`
C. `MnO_2` and KClO
D. `MnCl_4` and `COCl_2`

Answer 1

Correct Answer - B
`underset"Black powder"(MnO_2) + underset"conc."(4HCl) to MnCl_2 + 2H_2O + underset"Greenish yellow gas "(Cl_2)`
`Cl_2 + H_2O to 2HCl + [O]`
Coloured matter + [O] `to` colourless matter
`underset"Slaked lime"(2Ca(OH)_2) + 2Cl_2 to underset"Bleaching powder (white)"(Ca(OCl)_2) + CaCl_2 + 2H_2O`