Explain in which of the following , there is a change in oxidation number ? (a) Cr_(2)O_(7)^(2-) solution is madealkaline. (b) An aqueous solution of CrO_(4)^(2-) is acidified. (c ) SO_(2) is passed through acidified Cr_(2)O_(7)^(2-) solution. (d) CrO_(2)Cl_(2)is dissolved in NaOH.

Explain in which of the following , there is a change in oxidation num

1.	Explain in which of the following , there is a change in oxidation number ? (a) Cr_(2)O_(7)^(2-) solution is madealkaline. (b) An aqueous solution of CrO_(4)^(2-) is acidified. (c ) SO_(2) is passed through acidified Cr_(2)O_(7)^(2-) solution. (d) CrO_(2)Cl_(2)is dissolved in NaOH.
Answer» Solution :(A) `[ overset(+6) (Cr_(2))O_(7) ]^(2-) + 2OH^(-) RARR 2[overset(_6)(Cr)O_(4)]^(2-) +H_(2)O`. No change in OX. no. (v)` [2overset(+6)(Cr)O_(4)]^(2-)+ 2H^(+) rarr [ overset(+6)(Cr_(2)O_(7))]^(2-)+ H_(2)O`, No change in ox. no. (c )`[overset(+6)(Cr_(2))O_(7)]^(2-) + 3SO_(2)+ 2H^(+) rarr 2 [ overset(3+)(Cr)]^(3+)+ 3 [ overset( +6)(SO_(4))]^(2-)+H_(2)O` , Ox. no. changes (d) `overset( + 6) (Cr)O_(2)Cl_(2) + 2NaOH rarr Na_(2)overset( 6) (Cr)O_(2)`. No change in ox. no.