does colleges do campus selection based on percentage..... does 50% can get select and get seat of bsc

Yeah! For most of the colleges, the admission to BSc course is offered on the basis 10+2 marks. Now the basic eligibility criteria is that a student must have 45% marks in order to be eligible for the course. So if you have 50% marks then you are eligible for the course.

Now you will get chance or not is dependent on the status of the college. So you should apply for the colleges and as you have lesser marks I would say you should apply for more colleges in order to be safe from your side.

I hope this answer helps. All the very best for your future endeavors!