people say that ca prepares final a/cs and it is necessary to do illegal activities to hide real profits is it really true?

There is no compulsion do engage in illegal working in any profession / career, including that of carrer of CS's. Yes, you can interpret the laws in a different manner and work accordingly. As far as you are ethically & morally right, nothing is wrong.

Hey frnd First thing CA is not preparing Final accounts , CA is verifying Trueness and Fairness of final accounts and it is not the code of ethics of a Chartered Accountant to hide the real profits & do illegal activity , it is consider as behaviour of Professional Misconduct .