Major first. (+1)
B-flat to C-sharp is an augmented 2nd.
The interval from F sharp to D sharp is a major sixth. In terms of scale degrees, F sharp to D sharp spans nine half steps. This interval can also be described as the distance between the first and sixth notes of the F sharp major scale.
The interval from B-flat to D is a major third, regardless of the key.
it has a C sharp but no D natural
D-flat
a
B-flat to C-sharp is an augmented 2nd.
Major third
The interval from F sharp to D sharp is a major sixth. In terms of scale degrees, F sharp to D sharp spans nine half steps. This interval can also be described as the distance between the first and sixth notes of the F sharp major scale.
a flat( or g sharp),a, b flat( or a sharp), b, c flat (or b sharp), c, c sharp (or d flat), d, e flat (or d sharp), e, f flat( or e sharp), f, f sharp ( or g flat)and g.
a flat( or g sharp),a, b flat( or a sharp), b, c flat (or b sharp), c, c sharp (or d flat), d, e flat (or d sharp), e, f flat( or e sharp), f, f sharp ( or g flat)and g.
C sharp/D flat, D sharp/E flat, F sharp/G flat, G sharp/A flat, A sharp/B flat
The interval from B-flat to D is a major third, regardless of the key.
C, C sharp/D flat, D, D sharp/E flat, E, F, F sharp/G flat, G, G sharp/A flat, A, A sharp/B flat, B, C.
A D-flat is also an E-sharp in music. Technically, if you flat an E-sharp, you have an E, not a really flat D-flat.
if you are talking about notes: c c sharp/ D flat d d sharp/ e flat e f f sharp/ g flat g g sharp/ a flat a a sharp/ b flat b etc...
Bb to D is a major 3rd.