Hey,.

Yes you are eligible to apply for NDA exam. You just need time have passed your class 12th from a recognized board.

In order to be eligible for naval and air forces you need to have physics and mathematics in your class12th.

So you will be eligible for army but not fir naval and air force.

Below I have attached a link that contains detailed information about NDA exam and it's eligibility..

https://competition.careers360.com/articles/nda-eligibility-criteria

Hope that helps.

Thank you.