Class 12-science

You may join any of the below colleges:
1. Shri Chimanbhai Patel Institute of Business Administration Ahmedabad
2. Shrimad Rajchandra Institute of Management & Computer Application Surat
3. Ahmedabad University Ahmedabad
4. Navrachana University Vadodara
5. Ganpat University
6. RK University Rajkot
7. Shri R P Bhalodia College of Commerce and Business Management Rajkot
8. Navgujarat College of Computer Applications Ahmedabad
9. Fortune Institute of Management and Technology Baroda
10. Rai University Ahmedabad

You can do B.Sc hons. in maths,chemistry,computers or go for BA, BCA but since you want to crack CAT so join some institute as early as possible . We have so many institutes today for CAT coaching. Here is a comparison of some good institutes offering coaching for CAT -https://edudrona.com/right-coaching-institute-mba-entrance-cat-xat-mat-cmat-snap-tiss/?mref=tanu
Have a look.
And do as many internships as possible. It will help you build up your Resume and make you confident and help you in GD.

computer Science is really a good option for you. As the industry has been growing and been so demanding. It also provides a good opportunities for jobs in India and abroad also
As per your marks are not bad you could get admission in any good private college.
best of luck for your future.

if you interested in psychology then you can chose BA (Honours) psychology at Sam Higginbotom Institute Of Agriculture Technology and Sciences, SHIATS, allahabad, Uttar Pradesh and prepare for Tata Institute Of Social Sciences for MA psychology programme because here u can get more opportunities

https://hospitality.shiksha.com/hotel-management-colleges-in-pune-categorypage-6-84-1-0-0-174-114-2-0-none-1-0

Hi
Please use this link to know.
https://www.shiksha.com/jee-mains-college-predictor

from my side it will be from bsc with biology because with interest in study and good scope in biological field remaining ur dicesion

u can apply for diploma course on basis of 10 th result with diploma to degree in all medical & engg died ,computer , aviation so many option u are having