Translation:Quelle robe ?
"Quelle" needs a noun, it is an interrogative adjective: quel vélo ? quelle robe ? quels jours ? quelles fleurs ?
"Laquelle" is a pronoun, it can be used as a stand alone whenever you have a choice: lequel est ton vélo ? laquelle est ta robe ? lesquels sont tes jours préférés ? lesquelles sont les fleurs que tu veux ?
"laquelle est robe" = "which one is dress". It does not work, as you can see.
laquelle is a pronoun that you cannot use as an adjective: quelle robe ? or laquelle ?
By the way, you always need an article in French, so it should be "la robe". But still, that would make a different sense.
"Quelle" is an interrogative adjective that agrees in gender and number with the noun it modifies: quel vélo ? quelle robe ? quels jours ? quelles fleurs ? (which/what bicycle, dress, days, flowers...?)
"Que" starting a question is a pronoun: "que fais-tu ? (what are you doing?)
Ooookay, so the stem is 'Que' sort of, and the ending matches the gender & number? I think I got it!
Quick question, sorry if it's silly I thought we couldn't mention any item without defining it with la/le/des etc
does the Quel/Quelle define it depending on the masculinity?
You are right, in 99% of cases, nouns come with a determinant. A determinant can be an article (le, la, un, une) or an adjective: demonstrative (ce, cette...), possessive (mon, ma...) or interrogative (quel, quelle...).
All these determinants agree in gender (masculine, feminine) and number (singular, plural) with the noun they modify:
- quelle robe ? quel chapeau ? quelles robes ? quels chapeaux ?
This is the kind of lesson that makes me feel as if Duolingo is more like a game where you can practice some skills adcquired elsewhere in a REAL language course. It's a hell of a game, but still a game (a game of scrabble on steroids, if you will)