Hello Vikas,

For admissions into NITs, IIITs and CFTIs candidates must hav e passed 12th class or equivalent exam with a minimum of 75 percentage marks or must be in top 20 percentile (65 percentage for SC/ST Category candidates). But their is not criteria of 75 percentage to attempt JEE Mains exam.

To get more information about it go through below mentioned link.

https://engineering.careers360.com/articles/jee-main-2023#:~:text=JEE%20Main%20Eligibility%20Criteria%202023,-Particulars&text=There%20is%20no%20age%20limit.&text=Candidates%20must%20have%20passed%2010,examinations%20from%20a%20recognised%20board.&text=Candidates%20who%20have%20passed%2010,eligible%20for%20JEE%20Main%202023. %20the%20entrance%20exam.&text=Students%20can%20appear%20in%20the,attempts%20(April%20and%20May).

Hope this information was helpful to you.

All The Best!!