Breakdown of Vilket hus är svart?
vara
to be
huset
the house
vilket
which (ett) / what a (ett-word, exclamatory)
svart
black
Questions & Answers about Vilket hus är svart?
Why do we use vilket here instead of vilken?
The word for "house" is an ett word (ett hus). In Swedish, the word for "which" has to match the gender of the noun it goes with. Because hus is an ett word, we use the ett form: vilket. If we were asking about an en word, like en bil (a car), we would use vilken bil.
Why is the noun hus in the indefinite form instead of huset?
Just like in English, we say "which house" and not "which the house". After question words like vilken, vilket, and vilka, you always use the indefinite (basic) form of the noun.
Does the adjective svart also have to change to match the ett word?
It does, but you can't see it here! Normally you add a -t to an adjective when it describes an ett word. However, because svart already ends in a -t, it doesn't take an extra one. It looks exactly the same for an en word (en svart katt) as it does for an ett word (ett svart hus).
Why doesn't the verb come first since this is a question?