Hello..

No it's not necessary.

As you know those who have appeared for boards the same year also can give JEE mains examination.

For 12th passed students, you need to have 75% in CBSE or must be in top twenty percentile of their state boads.

For more information about this click here:

https://jeemain.nic.in/WebInfo/Handler/FileHandler.ashx?i=File&ii=3&iii=Y

Hello Kishore , Yes you are right. 75 percentage are compulsory in HSC to get NIT. In the Eligibility Criteria it is strictly mentioned that Students want to apply for NIT Should have more than 75 percentage in their 12th. Or student should be in top 20 percentile  in their 12 th. 

I hope it will help you.

Thanks. 

Which states are you talking about. Its very imperative to really clear the things because you need to be specific what are you talking about if you wish to seek solutions and resolve the querry. So be sure its specific and precise so that our team of experts could help you.