Hey Vibha!

You are very much eligible to pursure BA political science even if you haven't studied the same in 12th gradesince it's not compulsory to study Political science in 10+2 in order to pursue a bachelor's degree in it, there might be some percentage deduction in a few colleges but minor. Otherwise, if you have cleared 10+2 you are very much eligible to pursue BA Political science Honours.

Hope this helps!