The eligibility criteria for admissions to IITs and NITs is that a candidate must have scored and aggregate of 75% marks in his/her class 12th examinations or equivalent. So as far as you manage to score 75% in your class 12 or inter examinations, you are good to go. For more details check the link shared below:
https://engineering.careers360.com/articles/jee-main-eligibility-criteria
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