When `SO_(2)` is passed through acidified `K_(2)Cr_(2)O_(7)` solution

Options

A. The solution is decolourised
B. `SO_(2)` is reduced
C. Green `Cr_(2)(SO_(4))` is formed
D. The solution turns blue

Answer

C

Explanation

When `SO_(2)` is passed through acidified `K_(2)Cr_(2)O_(7)` solution, green chromium sulphates is formed. In this reaction, oxidation sate of Cr changes from `+6` to `+3`.
`K_(2)Cr_(2)O_(7) + H_(2)SO_(4) + 3SO_(2) to K_(2)SO_(4) + Cr_(2)(SO_(4))_(3) + H_(2)O`
The appearance of green colour is due to the reduction of chromum metal.