Question

what tense is the feminine mystique written in? first , third or omniscient?

Answer 1

Those are not tenses. Tenses apply to verbs. You are asking about the "person" of the narrative. "Omniscient" is a type of third person narrative.

See

http://en.wikipedia.org/wiki/Third-person_omniscient_narrative

for clarification.

Are you referring to the book by Betty Friedan?

That book seems to have a mix of narrative styles. The first person "I" appears often, but at times she makes omniscient statements of fact and her own opinions.