Identify the cases(s) where there in change in oxidation number.

Options

A. Acidified soltuion of `Cr_(2)O_(4)^(2-)`
B. `SO_(2)` gas bubbled throught an acidic solution of `Cr_(2)O_(7)^(2-)`
C. Alkaline solution of `Cr_(2)O_(7)^(2-)`
D. Ammoniacal solution of `CrO_(4)^(2-)`

Answer

B

Explanation

(b) (a) `overset(+6)(2Cr_(2))O_(4)^(2-)+2H^(+)+ to overset(+6)(Cr_(2))O_(7)^(2-)+H_(2)O`
(b) `overset(+6)(Cr_(2))O_(7)^(2-)+2H^(+)+3SO_(2) to overset(+3)(Cr_(2))(SO_(4))_(3)+H_(2)O`
(c) `overset(+6)(Cr_(2))O_(7)^(2-)+2OH^(-)+ to overset(+6)(2Cr_(2))O_(4)^(2-)+H_(2)O`
(d) `2NH_(4)OH+ overset(+6)(Cr)O_(4)^(2-) to (NH_(4))_(2)overset(+6)(CrO_(4))+2OH^(-)`
(e) `overset(+6)(Cr)O_(2)Cl_(2)+4NaOH to Na_(2)overset(+6)(Cr)O_(4)+2H_(2)O+2NaCl`