How to do CA?
Karthi, you can take up Science, Commerce or Arts, as there is no compulsion on stream for CA.
Since science seems better for you taking up science after 10th may be good for you. In this way you open up options in case after 12th you feel you would like doing something else other than CA.
Also if you still feel CA is your aim, after 12th, you may change to B.Com and do CA simultaneously. B.Com because CA is all about accountancy and B.Com is better to build a base in accounting subjects.
There are students who do B.Sc and CA but B.Com is advisable
You need to register with the Institute of Chartered Accountants of India (ICAI), which runs the chartered accountancy course in India. They are the only authorised institution in India for CA course.
You need to do your graduation degree simultaneously, while you would be clearing the initial courses of CA.
Once you are done with your graduation, you need to appear for the final exams of CA.
For step-by-step details on how to become a CA, visit the ICAI official website and check in the students section – http://www.icai.org/