"Is that your wife?"
Translation:Er det kona di?
My short answer is no. This is "det" used as an "empty" subject of the sentence, not "den"/"det" referring to sth specific. (as "that" in "That's my wife")
The long answer is that it would take a very strange, specific situation for that sentence to make sense. If you were looking at a gathering of wives and were asking a man "Is that one yours?" (literally: is that wife your wife), then I suppose "Er den kona di?" would be a grammatically correct sentence.