Dear Divya,

Selection is based on merit list of one of the following national level exams and also the minimum percentages for each category:

JEE-Main: General-60%, 54%-OBC-NCL, 30%- ST/SC/PWD

JEE-Advanced: General-60%, 54%-OBC-NCL, 30%- ST/SC/PWD

Kishore Vaigyanik Protsahan Yojana (KVPY)

To know further details about KVPY program: https://www.careers360.com/news/10109-all-about-kvpy-scheme-for-science-students

Eligibility: 

Students who have completed 12th standard with a minimum of 60% or First class or equivalent grade

Students must have Physics, Chemistry and Mathematics in +2 compulsorily; Biology, Statistics, Electronics and CS: Any of these can be additional subjects.

To know more about getting into IISc: https://engineering.careers360.com/articles/iisc-bs-admission

Hope this helps!