Are girls eligible to answer NDA exam??? What are the basic requirements to appear in the NDA examination????

Sorry to say you, but girls are not eligible for the National Defence Academy, The National Defence Academy eligibility criteria are as following:

Nationality
A candidate must be either be a
A citizen of India , or
A subject of Nepal, or
A subject of Bhutan, or
A Tibetan refugee who came ovbet ot India before the 01 January , 1962 with the intention of spermanently settling in India, or
a Person of Indian origin who has migrated from Pakisthan, Burma, Sri Lanka and East African countires of Kenya, Uganda, the United Republic of Tanzania, Zambia, Malawim Zaire and Ethiopia or Vietnam with the intention of permanently setting in India.

Sex:
Only unmarried male candidates are eligible.

Eligibility criteria:
For Army wing of National Defence Academy:
The applicant should be 12th Class pass

For Air Force and Naval Wings of National Defence Academy and for the 10+2 Cadet Entry Scheme at the Indian Naval Academy:
The applicant should be 12th Class pass of the 10+2 pattern of School Education or equivalent with Physics and Mathematics conducted by a State Education Board or a University.