Interrogative adverbs are used in questions. How much is used with uncountable nouns, whilst How many is used with countable nouns.

Interrogative adverbs Rule Examples
Why? (Perchè?) It is used only in questions.
  • Why didn’t you go to school yesterday?
When? (Quando?) It is used in questions to know the time or the period in which a certain action or event has taken place or will take place
  • When are you going on holiday this year?
Where? (Dove?) It is used in questions to know the place where a certain action or event has taken place or will take place
  • Where are you going on holiday this year? Maybe Croatia?
How? (Come?) It is used when the speaker wants to know the way in which something has happened or will happen.
  • How are you going on holiday? By car or by plane?
How much? (Quanto?) It is used only with singular uncountable nouns
  • How much shall I pay?
How many? (Quanti/e?) It is used with plural countable nouns
  • Here are the pencils. How many do you want?
Interrogative adverbs