CBSE 10th

If you get an IIM call, then these marks do not matter much. But to get IIM call, you need to score really very high more than 99 percentile. If you do so, then you can prepare for interview. Then, you will have to give some strong reason for such performance. You can then get in an IIM-prestigious B-School.

Qualifications: A graduation degree is a must, or a Diploma in event management certificate. Graduation will take you higher in this field. But getting a Diploma will start your career early but I'll suggest graduation will help you more, which will take place after 12th.

Yes, after class 10th you can go for:
Diploma in Business Administration: It will be of 3 years. It trains students in key business principles and helps them master management skills required at functional level.

Hello,
As you are still studying in 10th standard you should take commerce, economics and mathematics in your +2 and pass the same with a minimum of 50%. You have to clear ICWA foundation course named CAT and later on you could continue it.

As per your mentioned score you may have chances but sorry you can't get a call from IIM. But you can try to get admission in it.

As per your mentioned score you may have chances to get admission in top B-schools. You just have to get the procedure of counselling session or you can contact the college you are interested in.

First focus on 12th and get a good college. Also, do MBA from top IIMs i.e., A, B or C. Or if you have done sports or if you can do it then work on it and play you will get good money when you will play internationally. Or if you have interest in film industry then go for it as a career.

You can get a call from IIM if you lie in high percentile bracket and yes, you should appear for 2019 CAT. If you don't have job experience, it doesn't matter.

For diploma, you don't need to study 12th. You can join the same after 10th itself.

No, it's not easy to change it.