Questions & Answers about Questa idea è assurda.
Because idea is a feminine singular noun in Italian, and questa has to agree with it.
The demonstrative questo changes form depending on gender and number:
- questo = masculine singular
- questa = feminine singular
- questi = masculine plural
- queste = feminine plural
So:
- questo libro = this book
- questa idea = this idea
Even though English this never changes, Italian requires agreement.
For the same reason: adjectives in Italian usually agree with the noun they describe.
Here, assurda describes idea, which is feminine singular, so the adjective must also be feminine singular:
- masculine singular: assurdo
- feminine singular: assurda
- masculine plural: assurdi
- feminine plural: assurde
So:
- Questo piano è assurdo. = This plan is absurd.
- Questa idea è assurda. = This idea is absurd.