Hi Sagnik,
B.SC course is for a term of 3 years and there are lot of streams in B.SC like Chemistry, Biotechnology, Physics, Maths etc.
In west Bengal there are top collages for studying B.SC.
Some of the Government Colleges or Universities are

• Jadavpur University
• Maulana Azad College
• IISER, Kolkata
• Ramakrishna Mission Vidyamandira
• Lady Brabourne College
• Presidency University
• Vidyasagar College Kolkata

This are the few public/state runned colleges in west bengal for B.SC.
Hope this will help you.
Thank you