"Excuse me, are you Ivan Chernov?"
Translation:Извините, вы Иван Чернов?
It should if you also use the informal conjugation "извини". However, the question "Извини, ты Иван Чернов?" is just less probable because it can only be addressed to a child - normally, you don't address a stranger with "ты" unless they are a child. And for a child, the diminutive "Ваня" will be more appropriate.