Defence and aviation routes: NDA, pilot training, merchant navy
The routes where Physics and Mathematics, fitness and eyesight decide more than marks.
NDA
The Army wing accepts any stream; the Air Force and Navy wings need Physics and Mathematics in Class 12. The exam has a Mathematics paper, so Maths in Class 11 helps every wing. Fitness, the SSB interview and the medical are as selective as the written paper.
Commercial pilot
DGCA requires Physics and Mathematics in Class 12 and a Class 2, then Class 1, medical. Training is expensive; airline cadet programmes and the Air Force route are the alternatives. Get the medical done before spending on training.
Other entries
Technical Entry Scheme (Army) needs PCM. Agniveer and other non-officer entries have their own rules. Sainik and military schools are earlier entries, not Class 12 ones.
Guidance based on the CBSE scheme of studies and public exam bulletins. Confirm rules with your school and the official sources before deciding.