Hi

You didn't mention the category you belong to dear , to be eligible for admission in NITs, IITs  etc you need a minimum of 75% marks in class 12 or equivalent exam if you belong to general category . For those who are from SC/ ST category, they need a minimum of 65% marks in class 12 or equivalent.

Or

To be eligible you must be in the top 20 percentile in  class 12 examination

So check your eligibility as per your category, but if you don't fulfil the criteria, then you are not eligible for admission in NIT or IIT irrespective of how high  percentile you have got in JEE  examination

Thankyou