An Interrogative Pronoun is used to ask a question.

e.g. Who, Whom, Whose, Which, What.

( A ) Who ---- used for persons in general as subjects.

e.g. Who broke the window ?

      Who is laughing ?

      Who knows the answer ?

( B ) Whom ---- used for persons as objects.

e.g. Whom do you want to see ?

      Whom did she meet yesterday ?

      To whom did you speak ?

( C ) Whose ---- used to show possession.

e.g. Whose is this dictionary ?

      Whose is that book ?

      Whose is this coat ?

( D ) Which ---- used for both persons and things.

e.g. Which of three shirts do you like best ?

      Which is the right way to the Post Office ?

      Whivh of you knows my name ?

( E ) What ----- used for things in general.

e.g. What do you mean ?

      What is the matter with you ?

       What has happened ?