"What food is delicious?"
Translation:무슨 음식이 맛있습니까?
무슨 is a determiner, so it should be followed by a noun; your sentence is ungrammatical.
Can someone explain why the words are in this order please. In all the other examples the question word is in the middle. Why does it begin this one
Question words do not have to be in the middle. In this example, there is no middle since what food is the subject as a whole, not food alone.
Good question. For me, the correct answer it gave was not even a choice. 뭔 음식이 맛있습니까? Why was it not 무앗 음식이 맛있습니까?
I am not sure what you mean by a choice, but "뭔 음식이 맛있습니까?" is accepted. 무엇 is a pronoun, not a determiner, so it cannot come before a noun but should stand alone.
I'm still unsure when I should use 이 or 은 (I can tell when to use 는 because it needs a vowel before it. Same goes for 가 I think). And I know when to use 을 or 를 more or less... But yeah, sometimes I can interchange 이 and 은 but sometimes one is accepted but one isn't.