The correct scale for concert pitch C on a tenor horn is a C major.

Yes

A concert F on a trumpet is the G note. Since a trumpet is pitched in Bb, trumpet players will always play one note above the concert pitch. Along with that trumpet players will always play in a different key from the concert pitch. Trumpet players will add two sharps to the concert pitch. i.e. If the concert pitch is Eb, 3 flats, then trumpet players will play in the key of F, 1 flat.

trumpetman52

The bassoon is pitched in c-concert

Concert pitch or instrument pitch? The dominant 7th in the key of A is E G# B D, but that's concert pitch. If the orchestra is in A, the clarinet is in B, and the dominant 7th would be F# A# C# E.