hello harsh ,

To get admission in B.tech minimum percentage required is 50% but for IITs and NITs you need minimum 75% to get admission in B.tech in this colleges . 

Hii

35% marks are very low scores. As far as i know, there is no college which provides admission to such a low score. 50% marks in qualifying examination is the minimum eligibility for each nd every college. Rather some of the colleges have 75% as there basic eligibility.
Also JEE Mains, has its eligibility as 50% aggregate in class 12th with subjects physics, chemistry and maths.
So i would suggest you to work hard and study properly with dedication and concentration and try to score good marks so that you can get into some good college.

Thanks!!