Class 12-science

Yes, you can do a Diploma in radiology after 12th.

If you really want to pursue your career in aviation and will be satisfied with your life if you get a chance in it, then do it rather than regretting the whole life that you didn't achieve what you really wanted. But as you have lost the basics of maths, focus on it more and join a good coaching or better hire a good maths private tutor so that you will face no difficulties while practicing it.But you have also mentioned regarding your interests in biology. So be wise in making your decision. See what interests you more and will make you happy.

Graduates and post graduate in the field of psychology have several interesting opportunities in counselling and special education teaching. You may refer to following article for career details as a psychologist: https://www.shiksha.com/medicine-health-sciences/paramedical/articles/popular-careers-in-psychology-for-the-best-minds-blogId-3626.
You may opt for BA (Hons) psychology after 10+2.

It's like an ocean. You have plenty of option to choose over. Every human being born has a goal in life. Sit back and think over what you want to be in your future. In order work along towards it. You can choose course just like that, you need some dedication and passion. So request you to decide on what you want to study.

Check the below link for career options and respective fields future scope. You will get various career option after 12th medical/non-medical as per your interest -
https://www.shiksha.com/careers

You can go for IITJEE Mains, CET but I strongly prefer JEE Mains over anything else.

Diverse job opportunities exist in front of Architects. They may venture into sectors like Real estate, Infrastructure, Interior designing and teaching.
If you are interested in the core design job, the best way to get started is by working under established architects. By doing so, one will get valuable work experience and also get to learn tricks of the trade from the seasoned players!
B.Arch is good option for you.

Hi Prabhleen, please specify your subjects for better guidance.

Hi,
Some of the best-known colleges are:
Ramnarain Ruia College
St Xaviers College
Jai Hind College
SIES College of Arts, Science & Commerce