CBSE 12th

Computers is required because you are going to be taught about programming and coding in majority and subjects related to computer. So, it's better to have computers as a subject in class 12th and mathematics is also required because without mathematics, computer science is nothing. Science and commerce students, both can pursue BCA as their graduation.

After compelting your class 12th, you need to write SAT exam. This exam will get you into Bachelor's degree. You can go to each college and check if they have BBA. The college will ask you for SAT and TOEFL/IELTS. So, you need to get a good score in IELTS/TOEFL as well. Once you have these IELTS/TOEFL and SAT, you can write a statement of purpose which is required in every US college.
For MBA, you will need to write GMAT after completion of your Bachelor's, then you can again follow the same process.

Hello Vijay,
Yes, you can go for Merchant Navy. Just find an institute near you which gives training and course for merchant navy.

There are lots of exams to be given after class 12th to make a professional career. Please specify in which stream you are in so that it will help us in giving you good suggestions.

Hello Richa Kumari,
After 12th, please go for national level engineering entrance exams like JEE, VITEEE, SRMJEE, BITSAT, etc. and opt for either computer science or IT engineering.

Yes, you can and it is nice that you are not getting into rush.

Firstly, I would like to advice you to focus on gathering the knowledge and strong foundation on particular field, which you would choose for your career and second don't run for placement or packages. You should run only for education because best education will give you all tools and techniques to get best placement.
All the best.

As you are asking for entrance exams, you should first decide which course you want to pursue.
As per your marks I suggest you to opt for BBA or BCA.
If you are interested in science stream, opt for B.Sc in IT or computer applications.

CBSE is a board which is known and acknowledged not only in India but abroad too. Studying from Punjab board may not pose a problem in India but in Canada it will.