What are Interrogative Pronouns and Interrogative Adjectives?

What are interrogative pronouns?

Interrogative pronouns are used to start questions.

The interrogative pronouns are like this:

1. who (used as the subject of the question)
2. whom (used as an object, sometimes preceded by a preposition)
3. whoever
4. whomever
5. what
6. whatever
7. which
8. whichever
9. whose

In each of these cases, the pronoun has to be used both to replace a noun and to start a question in order to be considered an interrogative pronoun. Some of these words can function as adjectives when they modify nouns. Some are used as other types of pronouns in other types of sentences.

What are interrogative adjectives?

When one of the words above is employed as an adjective but begins a question, it is known an interrogative adjective.
Compare:

1. Which is yours?

"Which" is an interrogative pronoun.

2. Which hat did you choose?

"Which" is an interrogative adjective modifying the direct object "hat."