Hello Ritanjali!

If you are asking about any entrance exam based course then it is not possible to get a seat if you have not secured the minimum marks as defined by their respective exams. However, private institutions do have management quota through  which you can get a seat.

For other courses which do not have clear cutoff marks it depends widely on the institutions. Such courses usually admit students based on their marks in boards. However they too have a qualifying marks which is normally less than any of the entrance exam based college.