What is the action of acidified potassium dichromate on :
(a ) `SO_(2)`
(b ) KI
Draw structure of dichromate ion .

Explanation

(a) Action of acidified potassium dichromate on `SO_(2)` : Wehen passed through acidfied potassium dichromate solution , sulphur oxide gas is oxidized to sulphuric acid . The colour of the solution turns orange to green because potassium dichromate is reduced to chlorine sulphate .
`{:(3SO_(2)(g),+,K_(2)Cr_(2)O_(7)(aq),+,H_(2)SO_(4)(aq),to),("Sulphur",,"Potassium",,"Sulphuric",),("dioxide",,"dichromate",,"acid",):}`
`{:(K_(2)SO_(4)(aq),+,Cr_(2)(SO_(4))_(3)(aq),+,H_(2)O(I)),("Potassium",,"Chromic",,"Water"),("sulphate",,"sulphate",,):}`
(b) Action of acidified potassium dichromate on KI : When potassium iodide is treated with potassium dichromate it is oxidised to iodine . The colour of this solution changes to brown due to the liberation of Iodine gas . ,
` {:(K_(2)Cr_(2)O_(7),+,6Kl,+,7H_(2)SO_(4),to),("Potassium",,"Potassium",,"Sulphuric",),("dichromate",,"Iodine",,"acid",):}`
` {:(4K_(2)SO_(4),+,Cr_(2)(SO_(4))_(3),+,7H_(2)O,+,3I_(2)),("Potassium",,"Chronic",,"Water",,"Iodine"),("sulphate",,"sulphate",,,,):}`
The structure of dichromate ion is :