Science

Hello Prince,
There is no choice given to you for appearing in Maths papers. You can appear for Paper 1 if interested in getting admission into BE / B.Tech courses or appear for Paper 2 if you want to get into architecture. You, of course, have a choice of appearing for both papers. Paper 2 has three parts & one of the part is Maths. But opting for Paper2 & appearing only in Maths will serve no purpose. My advice, depending on where you want to go appear for either paper 1 or 2.
Best wishes.

No, if you are from home science, go in for human development. You can pursue your career in counselling as you can do D.Ed and teach primary section and B.Ed to teach secondary and junior college.

MBA aviation is very limited circuit in India. The cost for the education is very high and is available only at select few private institutes. Even then, the jobs aren't guaranteed.

You can appear for NEST and join NISER where you can pursue you degree in astronomy. CEBS is also a good option.

If MBA in aviation is offered by MBA schools, I am not aware of that. But just comparing the above two, MBA in HR has better prospects since in aviation you are constraining yourself to one industry rather than a specific function.

With B.Sc biotechnology, you can't get any decent job. You can go for M.Sc in particular field, then you will be able to get a decent job and salary.