(a) Sulphur dioxide gas turns a dichromate solution green. Write the reaction.
(b) Also write the reaction when nickel salts in basic medium react with dimethyl glyoxime.

Explanation

`({:(Cr_(2)O_(7)^(" "2-)+14H^(+)+6bar(e)to2Cr^(3+)+7H_(2)O),([SO_(2)+2H_(2)OtoSO_(4)^(" "2-)+4H^(+)+2e^(-)]xx3),(3SO_(2)+6H_(2)Oto3SO_(4)^(" "2-)+12H^(+)+6bar(c)):})/(Cr_(2)O_(7)^(" "2-)+3SO_(2)+2H^(+)tounderset(("green"))(2Cr^(3+)+3SO_(4)^(" "2-)+H_(2)o)`
(b) `Ni^(2+)` salts, in a basic medium, on reaction with dimethylglyoxime, give a cherry red precipitate of nickel dimethyl glyoximate.