Chemistry Spl

All the departments are at par with each other, however core branches have their charm.

You can consider B.Sc computer science as it is equivalent to B.Tech CS. You can become a software engineer after taking an additional small course after B.Sc CS.

Applied chemistry is used to know how chemistry is used in industry, society, environment, nanotechnology, polymer, etc. It's relevant to the industrial chemical which deals with the applications of chemical used in industries.

According to me, B.Sc in computer science is a good option as compared to others.

Hello,
Its a common conception that math is always tough :P
But, if you are interested in joining medical related courses or biotechnology then you must study biology. But you will be eligible to engineering courses as well.
If you choose C.S. you will be restricted to join engineering. As you say you are well versed in maths, I suggest you can take math+bio as your combination as the career & variety of courses will be wider.

Look, according to your marks you can easily get admission in DU's affiliated colleges, just fill the form and go for it.

Seems like you are qualified.
If you have got CRL rank in JEE Advanced, then you are definitely eligible for counseling.
https://www.resonance.ac.in/reso/news/jee-advanced-branch-allotment.aspx
Check this branch and IIT college predictor.