can pcmb is a good choice? if yes then tell me the scope
Yes its a great subject selection provided you should have the rigor to study Mathematics to be persistent in +2 level exams.
If you have PCMB then you will be eligible both for Medical as well as Engineering fields. Also if you want to pursue in basic sciences you will have a lot of choices in the pure , applied or interdisciplinary fields. If you have PCMB then you will have Biology to be the back-up subject which will definitely increase your marks in +2 level as well.
I hope my answer helps you. All the very best for your future endeavors!