B.Tech Scope

Percentage and selection is purely based on your number obtained in entrance test either by NEET or other exams.
After b tech you can go for m tech. Nowa days MBA n Civil services are greatly opted by engineering graduates. So think of your area of interest and go ahead.

you can not compare job opportunities like this. in which one you will be able to excel will fetch you a job.
In case if you take CSE and if you are not having aptitude to do programming how can you get jobs.

Yes biotechnology has very good scope. Biotechnology engineers are very high in demand for research in medicine in industry. If you're interested in this field, then definitely opt for it.
All the best.

in india there is very less scope for biotechnology.bt very opposite there is a lot of scope abroad.in india due to less contribution from india govt scope is less.u would get much better results in US and UK

Follow the article for details :
https://www.shiksha.com/career-as-computer-engineer-cc-31

IAS/PCS is certainly the best. you can also prepare for Bank PO. also there is option of SSC which can give u the very good job.

Scholarships are available if you have good profile and if you get 320+ in GRE. Only limited universities offer scholarships and few universities might wavy your fees if your profile is excellent.
Remember, scholarships are not so easily available as the competition is very high
All the best !!