The tonic triad is built on which scale degree?

The tonic triad is built on which scale degree?

• A. Fourth
• B. Second
• C. First
• D. Seventh

Answer: (C)

The tonic triad is built on the first scale degree, because that degree is the home pitch that defines the key. The triad formed there uses the notes 1–3–5, establishing the tonal center as soon as you hear it. In a major key this yields a major triad (for example, C–E–G in C major), while in a minor context the same starting degree gives a minor triad (A–C–E in A minor). The other degrees create different functions: the fourth degree forms the subdominant triad, the second degree the supertonic triad, and the seventh degree the leading-tone triad (usually diminished). So the chord built on the first scale degree is the tonic triad.

The tonic triad is built on the first scale degree, because that degree is the home pitch that defines the key. The triad formed there uses the notes 1–3–5, establishing the tonal center as soon as you hear it. In a major key this yields a major triad (for example, C–E–G in C major), while in a minor context the same starting degree gives a minor triad (A–C–E in A minor). The other degrees create different functions: the fourth degree forms the subdominant triad, the second degree the supertonic triad, and the seventh degree the leading-tone triad (usually diminished). So the chord built on the first scale degree is the tonic triad.