Yes, ofcourse you can take admission but before that decide which colleges do you want to join or shortlist few. 

Like for instance if you join University of Delhi you would be getting a deduction of 2.5% for changing the stream. So you can find out for other colleges as well and then take the right decision.

Dear student
I would like to tell you that yes he can definately go for b.com with C.A.
There is no strict rules that he cannot join the course.
Its just that he would have to do a bit of extra labour for understanding and knowing the new subjects as he will be switching from a non commerce background. 
All the best
I hope this was helpful to you.

Hey.

Yes. A candidate who has studied science and Commerce in 10+2 level can pursue B Com in graduation. There will be no problem with it.
Hope this helps. All the best.