An unanswerable question. You have to consider those which have been lost, and those of uncertain authorship. But hundreds.
Now pray tell, are we doing your homework for you?
How many movements are in Berlioz’s Symphonie Fantastique?
Five. The standard is 4, for the Romantic Era was all about breaking the rules.
What is the Moldau?
A river in the Czech Republic. The Czech name for it is Vltava.
What are most of Chopin’s pieces written in?
No idea.
Schubert and the art song - how many did he write? What forms did he use? Erlking - who is the poet?
Don’t know about the first two parts, but this link answers the question about the Erlking.