Question

balancing redox reactions occured in the basic solution : Cl2 + SO2(g) --> Cl^- (aq) + SO4^-2(aq)

Answer 1

I don't know how to do this without ending up balancing the equation and you need to learn how to do it yourself. Here is a site that explains all about redox equations. Post back here for specific questions. You need to know the change in oxidation state; for S it is from +4 to +6. For Cl it is from zero to -1(each).
http://www.chemteam.info/Redox/Redox.html