Which mode has half steps between 1-2 and 4-5 and starts on the seventh degree of the major scale (for example, white keys from B to B)?

Which mode has half steps between 1-2 and 4-5 and starts on the seventh degree of the major scale (for example, white keys from B to B)?

• A. Locrian mode
• B. Dorian mode
• C. Phrygian mode
• D. Lydian mode

Answer: (A)

Locrian mode is defined by starting on the seventh degree of the major scale and its interval pattern, which makes it unique in having half steps between the first and second degrees as well as between the fourth and fifth degrees. If you take the major scale and start on its seventh note, using only those scale notes, you get the sequence 1, flat2, flat3, 4, 5, flat6, flat7. On white keys from B to B (using C major as the parent scale) this becomes B-C-D-E-F-G-A-B. The half steps occur between B and C, and between E and F. That exact combination—half steps at 1-2 and 4-5—defines Locrian. You can also hear the characteristic sound in the B-D-F triad, which is diminished, matching the Locrian quality. Other modes do not exhibit both of those specific half-step placements, so they don’t fit the description as closely.

Locrian mode is defined by starting on the seventh degree of the major scale and its interval pattern, which makes it unique in having half steps between the first and second degrees as well as between the fourth and fifth degrees. If you take the major scale and start on its seventh note, using only those scale notes, you get the sequence 1, flat2, flat3, 4, 5, flat6, flat7. On white keys from B to B (using C major as the parent scale) this becomes B-C-D-E-F-G-A-B. The half steps occur between B and C, and between E and F. That exact combination—half steps at 1-2 and 4-5—defines Locrian. You can also hear the characteristic sound in the B-D-F triad, which is diminished, matching the Locrian quality. Other modes do not exhibit both of those specific half-step placements, so they don’t fit the description as closely.