Science

Yes, you can join the police force. The minimum eligibility criteria is a Bachelor's degree in any stream for UPSC (IPS) as well as for SI rank in the state police.

Both the courses possess equal importance. But if we talk about the employment opportunities then mechanical engineering is a better option. After completing B.Tech in mechanical engineering, several opportunities can be grabbed such as UPSE, UPSE IES, private sectors jobs, PSUs through GATE, etc. If you do B.Sc in Mathematics from a reputed college like IISc, ISI, etc., then you can do M.Sc, MCA, MBA, etc.
Top colleges for B.Sc are:
1. Indian Statistical Institute
2. IISc, Bangalore
3. Miranda house, Delhi.
4. St. Stephen's College, Delhi
5. Chennai Mathematical Institute
6. Institute of Mathematical Science, Chennai.

If you are interested in a pursuing career in Music then you can apply for B.A. In Music.

In case you are giving the subject specific M.Sc. Entrance exam then you can read books related to the subject and also basic aptitude questions you can pracitce from normal books and revise 10th and 12th knowledge.

Keeping the unemployment situations in consideration you should give top priority to employment because higher studies can also be done during the job. However, if you are getting chances of doing M.Tech programme through GATE may the best option.

You just need to shortlist the college of your choice and see the way that they take in students, through entrance test or through marks. You can apply and study.

At present age, biotechnology is a course that is in great demand and hence choosing it will give you a wide variety and explore in the future and the exposure depends upon the university that you will be choosing to complete your degree.

B.Sc science admissions have closed down in the sense that form application date has passed away. So you might have to wait for next year in order to get a chance in admission.