Hi Piyusha,

Its all depends on you. See there are many students who prepare for JEE Main and Advanced  rigorously for years and that time they hardly look at Computer Science subjects but after getting the good rank in JEE Advanced their first choice is Computer Science as it gives excellent placement.

Now those are the students who also get good placement so you cannot say that if somebody has not studied Computer Science subjects in past years then he/she cannot do further study of Computer Science.

Computer Science study is a skill and anyone can learn it at any point of time.

Now if we talk about eligibility criteria of Bsc in Computer Science then it asks you 10+2 in Science stream including Mathematics from a recognized board.

I hope this answer helps you.

All the very best!!