hey utkarsh

the probability of you to get admissions is low however it does not seems out of reach the merit list for St. Xavier's college is based on the index marks which can be calculated as 2*(maths % ) +physics% +aggregate % (out of 400)

i have calculated yours and it comes out to be 359.2 out of 400 but the last year cutoff was 380 out of 400 for cs of a cbse board student . it would be better if you have any category qota .here chech out the previous year merit list

https://www.sxcadmissions.in/list2018/BSR18L1.PDF

best of luck