What are the interrogative pronouns:

Interrogative pronouns are used to ask questions. What, which, who, whom, and whose are the principal interrogative pronouns. For example, who won the race yesterday? ‘Who’ is used for persons. To whom did you give the bill? Who is used for persons Whose is this? Whose is used for persons to show possession. What is the reply to the last algebra problem? What is used for animals and things? Which do you prefer? Which is used for persons, animals, and things. Whoever, whomever, whichever, and whatever can also be an interrogative pronoun. The interrogative pronouns with ‘-ever’ are used for emphasis or to show surprise. However, they are quite rare. For example: Whoever doesn’t love us some free time? Another example: Whatever is that? Sentences, including interrogative pronouns, are always questions, so they always end with a question mark.

Examples of interrogative pronouns:

Incorrect: He whom did you see at the store?
Correct: Whom did you see at the store? (Use “who” for the subject of the verb)
Correct: What’s your favorite hobby? Incorrect: What is you favorite hobby? (Contractions like “what’s” are allowed)
Correct: Which movie do you recommend? Incorrect: Which movie you recommend? (The pronoun comes before the verb)
Incorrect: Whose’s phone is that? Correct: Whose phone is that? (There’s no possessive apostrophe with pronouns)
Correct: Who wants dessert? Incorrect: Whom wants dessert? (“Who” for the subject, even with prepositions)
Correct: What time does the flight leave? Incorrect: What time do the flight leave? (Treat the singular “flight” as the subject)
Incorrect: I wonder who he loves more, me or her? Correct: I wonder who he loves more, me or her? (Repeated for clarity)
Correct: Which restaurant should we try tonight? Incorrect: Which restaurant we should try tonight? (The pronoun needs to introduce the clause)
Incorrect: Whose bookshelves are these piled so high? Correct: Whose bookshelves are these piled so high? (No need for an extra “are” before the pronoun)
Correct: Whom can I thank for this beautiful gift? Incorrect: Who can I thank for this beautiful gift? (Formal context uses “whom”)

Bonus Examples:

Correct: What were you thinking when you said that? Incorrect: What you were thinking when you said that? (Clause order)
Correct: Which shirt fits you better, the blue one or the green one? Incorrect: Which shirt you fit better, the blue one or the green one? (Agreement with subject)
Correct: Whose suitcase is packed and ready to go? Incorrect: Who’s suitcase is packed and ready to go? (Contractions okay for possessives)
Correct: What can I do to help you? Incorrect: What I can do to help you? (No unnecessary subject before the verb)
Correct: Which way is the library? Incorrect: Which way the library is? (Adverbial phrase follows pronoun)

Remember, interrogative pronouns introduce questions and should agree with the verb tenses and singular/plural subjects in the sentence. I hope these examples help you differentiate between correct and incorrect usage!