Science

Yes, you are able to apply in competitive exams like UPSC. The only condition is, that you should fulfill all the criteria of exam. Only being pass is not the case, cutoff is little higher

Yes, you will get admission. As per trends of last few years. Thanks.

B.Sc in AME course approved by DGCA is a better option in comparison to B.Sc. It is a specialised degree course with the potential high salary job as a maintenance engineer in the aviation industry.

Less marks in class 12th (Maths) won't matter in the graduation, unless you have no interest in Maths.
If you are interested in maths, then go for engineering and other courses like BA. But, if not interested, then go for B.Sc in different streams.

Dear,
It's difficult to confirm which college you will get with such rank. Chances of top college are less. So you can fill the form and take part in counselling or can take admission directly on management seat basis.

Dear,
You may consider these options:
Psychology
Forensic science
Agriculture
Computer science
Animation or visual communication
All the best.

Dear,
After B.Sc food technology, you won't get enough opportunities and you have to pursue Master's degree related to same.
Or, you can plan for B.Tech food technology, then you can start your job immediately after this.
Because, Food Technology has a great demand in market, and you can also think of MA or your own business module.
All the best.