Three ways of asking the same question?

what about c'est quoi un stylo, is that very informl, or just as acceptable?

This is the second time this question has been asked! This is partly because the lesson lacks clarity. My suggestion is that an explicit statement that these three are equivalent is included in the lesson. Also when the word something and chose appear in brackets and in successive examples, I suggest you use both with a slash in between,  i.e. (chose/something). Otherwise you have people like me thinking why are you saying ‘something’ for one example and ‘chose’ for the other.  The same applies where you use a simple noun ‘pen’ in one example and a proper noun  ‘le Sacré Coeur’ a place in the other. It would have been clear clearer to use both nouns as examples for all the forms of question to make it clear that those forms of question are equivalent. However, a clear statement that these three ways of asking a ways of asking a question are completely equivalent within the lesson would be helpful and would’ve avoided this question being asked twice already in the discussion. I hope my comments are useful.