Which one of the following statement is correct when `SO_(2)` is passed through acidified `K_(2)Cr_(2)O_(7)` solution?

Options

A. Green `Cr_(2)(SO_(4))_(3)` is formed
B. The solution truns blue
C. The solution is decolourized
D. `SO_(2)` is reduced

Answer

1

Explanation

In presence of moisture `SO_(2)` acts as a good reducting agent .It reducing character is due to the evolution of nascent hydrogen:
`SO_(2)+2H_(2)OrarrH_(2)SO_(4)2[H]`
Sulphur dioxide truns orange coloured potassium dichromatic solution green :
`{:(K_(2)Cr_(2)O_(7)+4H_(2)SO_(4) rarr H_(2)SO_(4)+Cr_(2)(SO_(4))_(3)+4H_(2)O+3[O]),(SO_(2)+H_(2)O+[O] rarr H_(2)SO_(4)"]"xx3),(bar(underset(("orange"))(K_(2)Cr_(2)O_(7))+H_(2)SO_(4)+3SO_(2) rarr K_(2)SO_(4))underset(("Green"))(+)Cr_(2)(SO_(4))_(3)+H_(2)O):}`