Hello

Yes, you can apply for NDA exam if you have completed your intermediate from open school/college. Also, you must be between 16.5 and 19.5 years of age. 

Thanks!

Yes, Private students can apply for NDA Entrance Exam. You should be passed or appearing class 10+2 from the recognized board. You can check the complete eligibility to apply for the exam with the given below link.

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

Good Luck!