45% are required in PCM in board exam for engineering admission. But instead of PCM ,can physics,maths,electronics % be considered?
No what is electronics. You might be in misunderstanding it seems. In class12 you have the main subjects as Physics, Chemistry and Biology or Maths nothing like electronics. So please consider PCM/B marks only for the further studies and admission. And for engineering consider maths as a main subject instead of Biology.