Dear Bunty,
This university do offers B.Sc. (Hons.) (Choice Based Credit System) in subjects like Botany, Zoology, Chemistry, Geology, Physics, Biochemistry, Microbiology, Biotechnology, Biophysics, Mathematics. If you want to do BSc (PCM) from Punjab University, Chandigarh then my answer would be, sorry, you look for other option. Candidates who wants to do B.Sc. (Hons.) Mathematics he/she should have passed 10+2 examination with at least 50% marks with Mathematics as one of the subjects. Detailed information can be obtained from Prospectus for PU -CET-2018 (UG) .
I hope it helps.