CBSE 12th

Dear Maheshwari Shinde,
You may choose B.Sc which has a good scope.

One of the exam you can give after class 12th for it is NCHMCT JEE.
It's registration starts in April starting and end within 15 days.
For further details, I suggest you to go through the following link.
https://www.shiksha.com/hospitality-travel/hotel-hospitality-management/exams/nchmct-jee

NIOS board can help you with this. Contact them and you can learn about the whole procedure. There exams are also easy and the board is eligible for most of the medical colleges.

First of all, I must say please take science only when you have even a little vision about what are you going to do after taking science in future.
Everything depends on your interest if you like something, then that thing becomes easy although it's difficult for others.

Academics are not the only parameters which IIM or any college around the world considers for admissions to various programmes though strong academics play a great role. There are other parameters like entrance exam score, group discussion, personal interview, aptitude test etc. Parameters would vary from college to college. They try to gauge the candidates skills from all the angles.

Absolutely yes, because they are the most stupid of all. They can do anything. They don't care for someone's career or anything. They will do whatever they want to.

You will need to check with the eligibility criteria of the college, which you are planning to take admission into. You should be able to make up. Still, consult with the college authorities.