Hello,
Considering that you are from CBSE Boards and you couldn't get an aggregate of 75 percentage in five subjects in class 12th boards, if you have given CBSE Boards improvement examination this year in one subject and then your percentage becomes 75 percentage or more, then yes, you are eligible for admission in NITs and IITs.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile