Someone who gives an answer for the sake of an answer

Solution 1:

If a person with a normal attitude receives a question to which he/she doesn't have an answer to, a reply would be "I have no idea. Why don't you look up the internet?" or "I don't know."

Know-it-all is the word describing;

A person who behaves as if they know everything

from Oxford Advanced Learner's Dictionary.

Someone who thinks he knows everything and refuses to accept advice or information from others.

from Thesaurus

Know-it-all can be used as an adjective.

8 Tips for dealing with a know-it-all coworker.

Solution 2:

Sounds like you're describing a charlatan

a person who pretends or claims to have more knowledge or skill than he or she possesses; quack.