Which is the singular pronoun in the sentence "She had to go back to home, because she forgot her bag."

Which is the interrogative pronoun in the sentence "What are others thinking about me? I do not care it."

Which is the relative pronoun in the sentence "That was the boy whom I saw in the party last night."

Which is the objective pronoun in the sentence "We lost our way, because we did not have guide with us in the dark forest."

Which is the interrogative pronoun in the sentence "Whom would you like to invite on your birthday party?"