Hello

https://www.google.com/amp/s/engineering.careers360.com/articles/new-eligibility-criteria-for-nits-and-iiits-admission-says-mhrd/amp

The above link will help you to get full details about IIT eligibility and full detail about iit admission.

Any more queries than free to ask

I hope it will help you
Good luck...

Dear Shubham,

To be able to appear for JEE Main and Advanced, candidates must be either in the top 20 percentile of students from their respective state or have a 12th score of atleast 75%. It is not compulsory to fulfil both the conditions. After this, you have to appear for JEE Advanced.

Both required for admission in IITs. But top 20 percentile is the primary factor and minimum 75% in CBSE is the secondary criteria.
Don't forget all your important documents like photographs, Jee advanced admit card, 10 and 12th marksheet, adhar card, samagra ID, transfer and character certificate from school. etc. Remember to have at least 2 copies of each document.
All the best.