B.Sc Chemistry

Do not worry. Confidently, go for B.Sc chemistry. It has a lot of career options in drug field.

Hello Baibhaba,
Bachelor of Science (B.Sc.) with specialisation in microbiology is a niche profile in India with a comparatively fewer job opportunities, but with tremendous scope in research. On the other hand, Bachelor of Science (B.Sc.) with specialisation in chemistry is a much more generalised course having comparatively more job opportunities. Both the courses are equally good and it depends whether the student is more inclined towards a job or towards research options.
I hope this answers your question to your satisfaction. If so, kindly upvote this answer. If you have any further questions, kindly revert.

Engineering is better, if you have interest then go for petroleum.

After B.Sc in chemistry either you can search for a job in various industries like chemical industry, pharmaceutical companies, petroleum companies etc. You can also join government jobs in the research field through CSIR NET or UGC NET exam. If you pursue M.Sc then you will have more options as mostly M.Sc chemistry students are being preferred in these industries.