Hyy sir, 

Yes, you are eligible for appearing in NDA ..But it will be very difficult for you to clear the exam as you are a non-maths student and there is a compulsory paper of mathematics in the NDA entrance exam in which question of 12th level of mathematics are asked..so its your choice if you want to take the exam..but I will suggest you to first go through the previous year papers of NDA and see whether you should actually sit for the exam..

If you are so interested to join the defence services you can appear for CDS and AFCAT after graduation..

I hope this helps