Breakdown of Vilka tomater är mogna?
vara
to be
tomaten
the tomato
vilken
which (en) / what a (en-word, exclamatory)
mogen
ripe
Questions & Answers about Vilka tomater är mogna?
Why is the word for "ripe" written as mogna instead of "mogena"?
The base form of the adjective is mogen. When an adjective ends in an unstressed -en, it drops that e before adding the plural ending -a. This makes it mogna instead of "mogena".
Why do we use vilka here instead of vilken?
Vilka is the plural form of the question word "which". Since you are asking about multiple tomatoes (tomater), the question word must match the plural noun.
Why does mogna take the plural form when it is at the end of the sentence?
In Swedish, adjectives must match the noun they describe, even if a verb like är (are) stands between them. Because tomater is plural, the adjective describing it must also take its plural form (mogna).
Does mogna only mean plural "ripe"?
It is also the definite form! For most adjectives, the plural form and the definite form (used with "the", "this", or "my") are identical. If you wanted to say "the ripe tomato", you would use this exact same form: den mogna tomaten.