The interrogative adjectives are used to refer to a noun in a question (also in an indirect one), when asking about the quality, identity, and quantity of someone / something.
In Italian there are three interrogative adjectives:
che / what, which
quale / which / what
quanto / how much
Che is invariable and can refer to nouns both in the singular and in the plural:
Che libro hai letto? (What book did you read?) —> libro = masc. sing.
Che libri hai letto? (What books did you read?) —> libri = masc. plur.
Che scarpe hai scelto? (Which shoes did you select?) —> scarpe = fem. plur.
A che ora passo a prenderti? (At what time shall I pick you up?) —> ora = fem. sing.
Quale has only one form for both the feminine and masculine gender, both in the singular (quale) and in the plural (quali):
- Quali programmi hai per stasera? (What plans have you got for tonight?) —> programmi = masc. plur.
- Quali ragazze hai già conosciuto? (Which girls have you met already?) —> ragazze = fem. plur.
- Quale libro vuoi? (Which book do you want?) —> libro = masc. sing.
- Quale canzone vuoi che suoni? (Which song would you like me to play?) —> canzone = fem. sing.
Quanto has four forms: it agrees both in gender and number with the noun it refers to:
- Quanto gelato hai comprato? (How much ice-cream did you buy?) —> gelato = masc. sing.
- Quanta pasta vuoi? (How much pasta would you like?) —> pasta = fem. sing.
- Quanti libri hai letto quest'estate? (How many books did you read last Summer?) —> libri = masc. plur.
- Quante canzoni hai scritto? (How many songs did you write?) —> canzoni = fem. plur.
