The difficulty with asking language-specific questions for a language you don't know is that if any of the answers differ from the ones you've been provided, you'll have no way of knowing whether they're correct or not. (I humbly submit that most of the responses thus far suffer from this flaw.)
Do you have a laptop that you can use to get them to code and see whether the result is what you want? If that's the case, simple queries are a nice place to start, and while you won't be able to judge the code's idiomatic style, you'll be able to see if it works:)
What the candidate likes and hates about the language is a good thing to ask, in my opinion. What would they change if they had the power to do so?