Which triad quality is built on the seventh scale degree?

Which triad quality is built on the seventh scale degree?

• A. Major triad
• B. Augmented triad
• C. Diminished triad
• D. Minor triad

Answer: (C)

When you build a triad from a given scale degree, you stack two more notes by thirds using the key’s diatonic notes. On the seventh degree, the triad uses the root, a minor third above (the third), and a diminished fifth above (the fifth). In a C major example, that’s B–D–F. The interval from B to D is a minor third, and from B to F is a diminished fifth, which together form a diminished triad. This is different from a major triad (root–major third–perfect fifth) or a minor triad (root–minor third–perfect fifth) or an augmented triad (root–major third–augmented fifth). So the triad built on the seventh scale degree is diminished.

When you build a triad from a given scale degree, you stack two more notes by thirds using the key’s diatonic notes. On the seventh degree, the triad uses the root, a minor third above (the third), and a diminished fifth above (the fifth). In a C major example, that’s B–D–F. The interval from B to D is a minor third, and from B to F is a diminished fifth, which together form a diminished triad. This is different from a major triad (root–major third–perfect fifth) or a minor triad (root–minor third–perfect fifth) or an augmented triad (root–major third–augmented fifth). So the triad built on the seventh scale degree is diminished.