Many students nowadays crack the CSIR itself after there BSc. Now as per my analysis the CSIR NET exam usually have syllabus more about BSc and moderate about MSc. So if you have proper background then you can obviously crack CSIR NET.

To know more about CSIR NET Chemical Sciences syllabus you may visit the link below:

http://csirhrdg.res.in/old_website/mcs_cs_sylbs.pdf

I hope this answer helps. All the very best for your future endeavors!