Political Science

You are eligible to change your stream from science to humanities after completing class 12th boards.

Hello,
Understand that the admission decision is up to the sole discretion of the college. The admission decision will depend on your overall profile and the selectivity of the college. So, nothing can be predicted. You should by the way specify more details such as your academic grades and also what you want to study for detailed advice.

In political science, you will get to know about Indian politics, rules and regulation, etc.

The PAC is formed every year with a strength of not more than 22 members of which 15 are from Lok Sabha, the lower house of the Parliament and 7 from Rajya Sabha, the upper house of the Parliament. The term of office of the members is one year. The Chairman is appointed by the speaker of Lok Sabha.

Law has much wider scope than Political Science. Many successful Politicians are actually law graduates.
After Pursuing law you can work in:
Law Firms
Independent lawyer after some years of experience
In Government departments like Human Rights commission, PSUs etc
You can prepare for Judicial Services
In my opinion you should opt for BA LLB where you can choose political Science as your BA subject.
Entrance Exams. - CLAT, SAT, BLAT, IPU CET, NLU D

According to the information available with me, it is around 45 percent marks. You need to score good marks in class 12th board exams to increase your chances of admission.