The evolution of red-brown gas on heating a salt with `K_(2)Cr_(2)O_(7)` and conc. `H_(2)SO_(4)` can arise from

Options

A. chloride
B. bromide
C. nitrate
D. nitrite

Answer

A, B

Explanation

`Cl^(-)+H_(2)SO_(4) to HSO_(4)^(-)+HCl`
`K_(2)Cr_(2)O_(7)+2H_(2)SO_(4) to 2KHSO_(4)+2CrO_(3)+H_(2)O`, `CrO_(3)+@HCl to underset("deep red")(CrO_(2)Cl_(2))+H_(2)O`
`6KBr+K_(2)Cr_(2)O_(7)+7H_(2)SO_(4) to underset("Red colour")(3Br_(2)) uarr +2Cr^(3+)+8K^(+)+7SO_(4)^(2-)+7H_(2)O`