Yeah! You are eligible for the entrance examination provided you should have satisfy the minimum requirement as preferred by the Entrance examination authority.

For JEE MAINS paper 2 you must have 75% marks in your 10+2.

To know more about JEE MAINS paper 2 you may visit the link below:

https://engineering.careers360.com/articles/jee-main-paper-2-syllabus

To know more about NATA you may visit the link provided below:

https://engineering.careers360.com/articles/nata-eligibility-criteria

To know more about BArch visit the link below:

https://www.careers360.com/courses/b-arch-bachelor-of-architecture

I hope this answer helps. All the very best for your future endeavors!