Which subjects should I choose in 11th class according to the CBSE schooling?

You must have Physics, Mathematics as a basic subject with computer Science. And, you must also be good in operating the system, because it helps in you designing the aircrafts. Physics is the main and essential subject for the AE.

To apply for aeronautics after class 12th, you should have Physics Chemistry and Maths with Computer Science, because to become an aeronautical engineer you should have knowledge of Physics, and known about the Mathematics like differentiation and integration, you should also have some basic knowled

Since your interest is in aeronautics, then PCM would be a best choice for you. Moreover, you can choose any subject for additional subject, it hardly matters to you. Aeronautical engineering has a lot to do with mechanics, physics and maths.

It totally depends on your interest. If you want to pursue engineering or medical go for Science, else you also have commerce or maybe arts. But, remember one thing don't decide your branch under the influence of anyone. It won't work that way.