Hi Alok, 

For admission in St. Xaviers' Kolkatta for a B.SC in Physics you can simply login to their website and fill up the form. However, the form has not yet been released. It will be tentatively out in June. The application form will cost you around Rs.1000/-/ As far as the subject-comibination is required in order to be eligible for admission in B.SC Physics or B.SC Chemistry at the said institute, if you had Physics or Chemistry (as the case may be) in +2, that will be enough. Biology instead of Math is not a bar to admissions. To know more about the college and the course kep reading Careers 360 using the link given below: 

https://www.careers360.com/colleges/st-xaviers-college-kolkata

Thanks,