F-sharp minor
Mozart's only composition in this key is the second movement to his Piano Concerto No. 23 in A major. 2 of Chopin's 52 mazurkas, and 1 of his nocturnes are in this key, though he seems to have liked the related key C-sharp minor better. Scriabin's Piano Sonata No. 3 is also in this key, and the 3rd movement of Beethoven's "Hammerklavier" Piano Sonata is too.