Science

Of course, you can pursue M.Sc in nursing after completing B.Sc in nursing. In fact, many colleges would prefer a B.Sc in nursing graduate as they are already familiar with the basics.
Thank you.

1) Read chemistry textbooks as much as you can.
2) Ask professors in your school for advice.
3) If you want to specialize in chemistry, opt for B.Sc (Chemistry), which is a gateway to higher studies in Chemistry.

Please refer to the link mentioned below for the list of colleges which offer M.Sc through correspondence or distance:
https://www.shiksha.com/science/colleges/distance-correspondence-m-sc-colleges-india

BA and B.Sc are different fields. If you opt for B.Sc, you will be placed in the scientific cum technical field. After BA, you would have to pursue arts as a career. If you want to appear for civil services, either of the two should suffice. You should opt for the course you are comfortable with and where your interests lie.

Please refer to the link provided below for details on M.Sc. electronic media from Anna Malai University, Chennai and its placements:
https://www.shiksha.com/science/course/m-sc-in-electronic-media-anna-university-guindy-chennai-167650

Please refer to the link provided below for details regarding admission in M.Sc (Agronomy) in Amity University, Noida:
https://www.shiksha.com/science/course/m-sc-in-agriculture-agronomy-amity-university-noida-232553

Please refer to the link provided below for a list of entrance exams for a course in B.Sc:
https://www.shiksha.com/science/articles/top-bsc-msc-entrance-exams-in-india-blogId-13484
Different colleges have different criterias. Candidate should download the brochure of each college seperately to get a fair idea of their eligibility.

Please refer to the link provided below for a list of colleges for PG in Science (Biology):
https://www.shiksha.com/science/colleges/m-sc-biology-colleges-india