postulate vs ask

postulate is a noun but ask is not a noun.

Word	Noun	Adjective	Verb	Adverb
postulate	Yes	No	Yes	No
ask	No	No	Yes	No

As verbs, postulate and ask are synonyms defined as:

Other synonyms of postulate include call for, demand, involve, necessitate, need, require, take.

postulate (noun)	ask (noun)
(logic) a proposition that is accepted as true in order to provide a basis for logical reasoning

postulate (verb)	ask (verb)
take as a given; assume as a postulate or axiom	make a request or demand for something to somebody
maintain or assert	direct or put; seek an answer to
require as useful, just, or proper	address a question to and expect an answer from
	consider obligatory; request and expect
	require or ask for as a price or condition
	make a date
	require as useful, just, or proper