B.Sc

Look Aswin, your BSC Maths is not a big deal. Because, the maths which asked in Entrance exams is of std 10th level Maths ( of NCERT/CBSE level Maths ). Don't be panick. If you want to join institute for preparing for CAT, XAT, MAT, CMAT, SNAP, NMAT, etc. I will suggest you to join T. I. M. E. It is the best institute for preparing for entrance exams in India. It will give you support for all syllabus and help you in GD & PI Round also. Best of luck for your future !

For ethical hacking you may opt for bca rather going for bsc physics. For ethical hacking there are certification that you have to grab. Courses like CCNA CCNP etc are done for these international certifications.

Every subject is fruitfully. Civil services has very vast meaning. When you will start preparing you will prepare math science geography history hindi etc etc. There you will be benefited if some questions related to your subjects are asked if. Nevertheless go ahead. Or i would recommend if civil services is our ultimate goal them opt for Botany zoology chem. Or physics math chem.

What do you mean by term content?
It's contain courses on computer software, language, programming, mathematics, hardware etc. If you are good in mathematics and logic and have some basic knowledge of computer languages like C or Java, definitely it will help you.

Rahul with Physics you can opt for an intresting technical career. You can aspire to join ISRO for example. You can do research in this field after post graduation. You can, if you attain requisite skills, go ahead and start manufacturing measuring meters & instruments of several kinds. You can be a Professor in the college. You can even opt for a career in Forensic science.

Between the two and if other things are equal then I would suggest Ruchi that you got with Chemistry. You will then have wider oprtions in your career.