Answer:

fsharp

Answer	Crossword Clue
FSHARP	G flat?
FSHARP	G neighbor
FSHARP	Key of Beethoven's Piano Sonata No. 24

FSHARP	Major scale in which B is the only natural
FSHARP	Half step below G
FSHARP	Irving Berlin's key
FSHARP	Key of Mahler's Symphony No. 10
FSHARP	Tough key for pianists
FSHARP	Half-step below G
FSHARP	Only key Irving Berlin composed in
FSHARP	Key of Scriabin's Piano Sonata No. 4

FSHARP	Key of Chopin's "Barcarolle"
FSHARP	Musical neighbor of G
FSHARP	Key that's oxymoronic at school?