Hello dear student!

IITs and NITs are among the top institutions for engineering in India. You need to score very good in JEE in order to make through them.

Yes, definitely, you require to get 75% marks or should be in top 20 percentile in your 12th boards in order to be eligible for IITs and NITs.

Well, if you belongs to SC/ST category, then requirement is 65% .

Hope this helps