Chemistry Spl

If you take B.Sc in computer science as your subject then you will have to study statistics, electronics, maths and of course computer science.

B.Sc. Chemistry is a specialised course for students who wish to learn the fundamentals of chemistry and various branches of chemical science. Having learned the basics of Chemistry in 10+2, students can expect to gain an in-depth knowledge of how chemicals and chemical processes work. This course prepares a student for challenges in the chemical industry.
This course also addresses the rabid changes going on in the chemical industry and provides students with enough insights to adapt to new developments and changes in the field of chemistry.

You have to qualify in both the subjects if you want to pursue engineering. You have no other option.

Personally, I opt for hotel management. It is vocational. chemistry may not produce a direct benefit.

Why do you want to change your college for B.Sc in chemistry as you are doing B.Sc in biotechnology so it has really a good scope in future so don't worry about the college and study in the source you have and try to score good and achieve sometimes better from them.
All the best!

I will suggest you to go for Chitranjan Bhakta. But this is only for organic chemistry.