(A) Chromyl chloride test: 4Cl−(s)+Cr2O72−(s) + 6H+(conc.) → 2CrO2Cl2 ( deep red vapours ) + 3H2O When deep red vapours are passed into sodium hydroxide solution, a yellow solution of sodium chromate is formed, which when treated with lead acetate gives yellow precipitate of lead chromate. CrO2Cl2+4OH− → CrO42−+2Cl−+2H2O CrO42−+Pb+2 → PbCrO4↓ ( yellow)