Hello shubham,
Yes, you are eligible.
The minimum educational qualification is a 10+2/ Intermediate with a minimum aggregate of 50% marks. Candidates wishing to apply for B.Arch admission in IIT are required to appear for JEE (Advanced) exam.
Here is the link for more detail about eligiblity
https://www.google.co.in/amp/s/engineering.careers360.com/news/cbse-specifies-eligibility-for-barch-bplanning-courses-in-nits-and-cftis/amp
Thank you.

Hiiii

Yes you are eligible to apply in NIT but you will have to qualiy the Part2 paper of JEE Mains entrance exam. 
B.arch admission in NIT is done through JEE (Main) exam ie. Part II of JEE Main exam (aptitude test for architecture). Candidates are offered admission based on all India rank of the exam through online counselling.The minimum eligibility for candidates applying is class 12 (intermediate) with mathematics as a subject and a minimum total percentage of 50 percent marks. 60 percent weightage is given for entrance exam marks and 40 percent for class 12 exam marks during selection.

Hope this helps.

Thanks!!