Hello Bhumika!
The basic eligibility criteria for M.Sc. Criminology is having a bachelor's degree in science stream with atleast 50% aggregate marks.
So, based on this, if you have done your B.Sc. in Chemistry, then you will be eligible.
Admission is usually provided based on marks obtained in entrance exam conducted by the individual college/university and your graduation percentage.
Though the criteria may have some variations depending on the institute.
Kindly comment below the name of the college you are interested in to get more information.

Hope this answer will help you.