I am having maths as additional subject in 11th class and biology as main subject .So,can I apply for NDA exam
The eligibility criteria of NDA exam for Indian army is 12th pass in 10+2 pattern and Indian navy and air force is 12th pass in 10+2 pattern with physics, chemistry and maths. So if you have PCM in your 12th you are eligible. Candidates appearing in 11th exam are not eligible.
You can check the below link for more details.
https://www.upsc.gov.in › filesPDF
Notif-NDA-NA-II-2021-Engl-09062021_0.pdf - UPSC
Hope this helped.
All the best!