CBSE 12th

Hi,
Yes, you can pursue BBA in aviation management even if you are from arts stream.
Good luck.

If you could score anywhere around 250, your chances of getting into mechanical engineering, NIT, Tiruchirappalli are pretty high. However, I'd advise you to not settle down on the fixed score of 250. Always try improving on the areas you're weak and strengthen the topics you're good at. Fix a target more around 280-300 and start working towards it now that you have time. Good luck!

You can do Diploma in this field, but I would suggest you compare it with BBA in aviation management which is a highly professional course and then decide what to do.
Regards.

There are various good courses which you can do after class 12th if you opted for science stream. You can become a doctor, teacher, engineer, analyst or researcher.

If you really want to get a good college for aviation, 50% marks will not help you to get into a good government college so search for universities like GGSIPU which conduct their own entrance exam and try achieving a good rank there so that you get a good college.

Yes, you can get the admission.

The minimum fee for CPL starts from 20 Lakhs.
Every academy has different fees.

Engineering and J&M are very different from each other. While you have to exert a lot more for engineering, it will be more fruitful. But if you actually want to do Journalism and Mass Communication then you should go for the course you really want to pursue.

For PG Diploma in industrial safety management you ought to complete graduation from a recognized university.
The PG Diploma full time course is of 1 year. You can get into 1 year Diploma in fire and safety.

Here are the career prospects after bio chemistry:
You should do M.Sc biochemistry. You can do M.Sc chemistry if you have chemistry as a core subject in all 3 years of B.Sc. 12th subjects don't matter much.