exact vs necessitate

exact is an adjective but necessitate is not an adjective.

Word	Noun	Adjective	Verb	Adverb
exact	No	Yes	Yes	No
necessitate	No	No	Yes	No

As verbs, necessitate is a hypernym of exact; that is, necessitate is a word with a broader meaning than exact:

Other hypernyms of exact include ask, call for, demand, involve, need, postulate, require, take.

exact (adjective)	necessitate (adjective)
marked by strict and particular and complete accordance with fact
(of ideas, images, representations, expressions) characterized by perfect conformity to fact or truth; strictly correct
lacking compromising or mitigating elements

exact (verb)	necessitate (verb)
claim as due or just	require as useful, just, or proper
take as an undesirable consequence of some event or state of affairs	cause to be a concomitant