What can I do after completing a BSc in physical science?

You have so many options.If you are interested in teaching profession,you can go for MSc and then for BEd or MPhil/Phd.If you are interested in technical jobs,you can try for that,many private and public sector companies recruit physics graduates.Also if you are interested in management side,you can do MBA.You can also try for PSC,UPSC,SSB exams.