A mixture of three gases A,B and C is passed first into acidified `K_(2)Cr_(2)O_(7)` solution when A is absorbed turning the solution green. The remainder of the gas is passed through excess of lime water which truns milky resulting in the absorption of B. The residual gas C is absorbed by alkaline pyrogallol solution. However the original mixture does not run lead acetate paper black. Identify A,B, & C ( Give necessary equations ).

Explanation

(A),(B) and (C ) are `SO_(2),CO` and `O_(2)` respectively. The reactions are as follows `:`
`K_(2)Cr_(2)O_(7)+H_(2)SO_(4)+3SO_(2)rarr K_(2)SO_(4)+underset(("green"))(Cr(SO_(4))_(3))+H_(2)O`
`Ca(OH)_(2)+CO_(2)rarr underset("milky")(CaCO_(3)darr)+H_(2)O`