"When are you opening the restaurant?"
Translation:Restoranı ne zaman açıyorsunuz?
I was looking for that answer too, then I remembered it. I made the same mistake by thinking that the subject of the sentence is the 'restoran' therefore no 'ı' should be added. But here the ''restoran' is the object of the verb Acmak, so 'ı' is added. I have no idea what the subject of the sentence is.
"Ne" is "What", "Ne zaman" would be "What time" literallym so - "When" Ne istiyorsun? - What do you want? Restoranda ne yiyoruz? - What are we eating in the restaurant? Ne zaman restorana gidiyoruz? - When are we going to the restaurant? Bunu ne zaman bitireceksin? - When will you finish it?