2. A policeman whom I met showed me the house.
Whom is a relative pronoun of the masculine gender, singular number, and third person, agreeing with its antecedent, policeman. It is in the objective case, being the direct object of the transitive verb met.
3. The corporal, whose name was Scott, came from Leith.
Whose is a relative pronoun of the masculine gender, singular number, and third person, agreeing with its antecedent, corporal. It is in the possessive case, modifying the noun name.
4. Whose birthday do we celebrate in February?
Whose is an interrogative pronoun in the masculine or feminine gender, singular number, and possessive case, modifying the noun birthday.
5. He injured himself severely.
Himself is a compound personal pronoun of the third person, used reflexively. It is of the masculine gender, singular number, and third person, agreeing with its antecedent, he. It is in the objective case, being the direct object of the transitive verb injured.