See the marks required for admission is entirely dependent on the status of the college. But the basic educational qualification you must have is that you must have passed 10+2 with a minimum marks of 50%. Now this makes you eligible for the course. Now the marks required for admission is dependent on the colleges. For example, there can be some not so famous colleges which can offer BA course via merit list, then the number of applicants applying for that college definitely go lesser than that of the good college or the range of marks deviation will be less in such colleges. So if you have average marks then you have a good chance there. But if you have applying for top colleges say like St. Stephens college then you will need above 90% or else you can't even compete to the merit there. So its very much dependent on the competition in the college. If you have average results and you want to go for good colleges, then I would recommend you to go for colleges which conducts entrances. This will atleast increase your possibilities.

I hope this answer helps. All the very best for your future endeavors!