Greetings! 

If seen in terms of direct job oppurtunities,  then B.Sc in chemistry is more preferable.  But in terms of indirect job oppurtunities,  B.A. in political science is better.  By indirect , i mean that the latter would provide you a strong base for the UPSC. So , if you want to join UPSC,  then go for B.A. in political science,  otherwise B.Sc in chemistry.

Hope it helps!