Learn French: Quelles robes est-ce que vous achetez ?

The interrogative adjective quel (which/what) has to agree in gender and number with the noun it describes. Since robes (dresses) is feminine and plural, we must use the feminine plural form quelles.

Do quelles and quel sound different when spoken?

No, they sound exactly the same! All four forms (quel, quels, quelle, and quelles) are pronounced identically, sounding a lot like the English name 'Kel'. You only notice the difference in writing.

Why is quelles placed before robes?

Just like the English phrase 'which dresses', the interrogative adjective quel (and its variations) is placed directly in front of the noun it is asking about.

Can I ask this question without using est-ce que?

Yes! You can use inversion (swapping the verb and subject) to ask the exact same thing: Quelles robes achetez-vous ?. Using est-ce que is just a standard, slightly less formal way to build the question.

Why is there no accent mark on the word achetez?