For BSc Mathematics if you get enrolled in the course then there are options you can take Physics as your Generic Elective. But in general, being a commerce student you can get admission in BSc is quite strange but if you get the subject then also you have to work hard if you take physics as you have to know some of the basics from the 11 and 12th.

So be aware of the step you are taking.

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