Hi,

There are many Government Colleges which do admission on the basis of merit prepared by the respective institutions of the marks you have got in class 12 examination.
For every institution ,there are different cutoffs.
Many Universities conduct Entrance examination and on the basis of results and cutoffs ,you can take admission into that institution.
If you want to take admission in the government institution ,you have to fill up the admission form and follow the eligibility criteria for the course.
The eligibility criteria for doing a b.sc in forensic science is to have 55% aggregate marks in Physics , Chemistry, Mathematics/Biology stream.

Hope it helps.

Best Wishes