"Who knows the answer to this question?"
Translation:Кто знает ответ на этот вопрос?
I thought it would be кто знает ответ на этом вопросе, because на would require the prepositional case here, but I was wrong
I thought the same, but can anyone clarify why the prepositional case was not used here?
Prepositional case is only used with на when talking about where something is located. When talking about movement TO a place, or knowing the answer TO a question, accusative is used.
Why not "Кто знает ответА на этот вопрос"? I thought that abstract nouns can take the genitive ending instead of the normal accusative when they are direct object.