Dear omprabh,
In brief:
1. Leave provided by company (EL, SL & CL) are governed by appliable labour law statute - i.e. Shops & Establisment, or as per the Company's Leave Policy (which is given over & above the appliable leave as per relevant statute)
2. If you are covered under S&E Act, check the relevant state's act appliable to you, because few states provide CL & SL but many do not.
3. If you are not covered under any statute for providing leave, then your company's leave policy decides the quantum of leave and eligibility.
4. Generally leaves (CL, SL & EL) are earned and availed on pro-rata basis. Ex: If employee is eligible for 12 days CL in a year, he can avail only one day after completion of one month (hypothetically). If additional leave taken can either be granted as paid leave as a very special case, or treated as Leave Without Pay. Depends on the company's HR apporach & spirit of the polcies.
Hope the brief gives you insights to resolve your queries.
Regards
Ketan Shetty