B.Sc

Dear Student,
You asked about Belur vidya mandir which is actually Ramakrishna Mission Vidyamandir. The first thing it does not offer BSc in Chemistry or industrial chemistry and second if you are asking about B.Sc. (Hons.) in Physics, then you can check the below link for further details.
https://www.shiksha.com/college/ramakrishna-mission-vidyamandira-howrah-52978/courses/bsc-bc

The cutoff for B.Sc is 93% to 95%.

You can go with medical also in M.Sc. It will be beneficial in future for you.

Choose what you love. Also look at the curriculum and the university. Pursue career in microbiology only if you get admission in a good and prestigious institute. Zoology is a core subject and hence offers a wide range of career opportunities whereas microbiology is an specific course. Although there are bright opportunities in microbiology but look for some good institute.

JIS University, SRM University, Tamil Nadu Agricultural University, Mahatma Phule Krishi Vidyapeeth, Bisra Agricultural University, Khalsa College etc.

Amity University, Banasthali Vidyapith, University of Rajasthan, Jaipur National University etc.

Mount Carmel College, Kristu Jayanti College, Reva University, Dayananda Sagar University etc.