I am PCB student in class 11. I want to continue MATH but no school near me has PCMB stream. so, can I give MATH exam from NIOS (nation institute of open schooling) before i pass my 12 standard. I mean can i continue PCB from my school and prepare MATH and then give it's examination through NIOS.
The idea that you have proposed is good, but NIOS generally requires that though you can re-take your class XIIth examinations, but the time of taking examinations have to be separate years. Like say you will give your class XIIth exams in 2022, then you should appear for the NIOS maths paper after your official class XII exams have ended.
Hope I have answered your question. All the best!