If you wish to get into NIT then you not only need to have a good rank but you also have to pass all the subjects in your 10+2. If you fail to do so, then despite of having a good rank for the admission to NIT's, you will not be granted admission to the course of BTech in NIT's.

For more information regarding JEE MAINS consider the link below:

https://engineering.careers360.com/articles/jee-main-eligibility-criteria#:~:text=No%20age%20limit%20to%20appear,apply%20for%20the%20entrance%20exam.&text=Students%20can%20appear%20in%20the%20JEE%20Main%20exam%20for%20three%20consecutive%20years.

I hope this helps. Wish you a great eve!