UPSC

This is more of a personal choice and dependent on your preference for job profiles, for example, to appear in UPSC Civil Service Exam you need to attain 21 years and pass graduation in any field from a recognized university, there is no specific aggregate required, for this administrative career there is no requirement of post-graduation, graduation is enough, on the other hand, you should go with M.Sc. Chemistry if you're more interested in academics or teaching, you can go for various entrance exams such as IIT JAM CSIR NET etc., you can become an assistant professor, you can also teach in a school for that you need to have B.Ed and with M.Sc. You can become PGT as well, both the options are good in their own way, it's up to you to decide on which path to follow.