Hi Anuciya,

Its very much possible if you want to pursue b.com (hons)after 12th from Tamil Nadu. Despite of studying Science stream. Basic criteria for b.com  (hons) is to have maths in your 11th and 12th and you have got a very good marks in your 12th. However, it's just that your need little work hard on your accountancy and economic. 

Wish you good luck.