Who's coat is that?
The possessive form of who is "whose." In this sentence the author is wondering who the coat belongs to, or who possesses the coat. "Who's" is only used to mean "who is" and "whom" is the objective form of "who."
940 MCQ for effective preparation of the test of Nouns and Pronouns of English Grammar section.
Read the MCQ statement: Who's coat is that?, keenly and apply the method you have learn through the video lessons for Nouns and Pronouns to give the answer. Record your answer and check its correct answer and video explanation for MCQ No. 103-4382.