What type of scale includes all twelve notes of an octave?

The type of scale that includes all twelve notes of an octave is the chromatic scale. This scale is constructed by including every semitone within the range of an octave, meaning that it progresses through all the pitches available in Western music before returning to the starting pitch at the octave.

For example, starting from C, the chromatic scale would include C, C#, D, D#, E, F, F#, G, G#, A, A#, B, and then C again. This inclusivity of every note creates a scale that is versatile and often used in various musical applications, such as modulation and improvisation.

In contrast, the other scales mentioned focus on specific subsets of notes or intervals. The scales of a minor typically include seven notes derived from a specific pattern of whole and half steps, while the whole tone scale consists of only six notes, built entirely of whole steps (e.g., C, D, E, F#, G#, A#). The harmonic scale also does not cover all twelve notes, typically following a specific minor sound structure with a raised seventh degree, making it distinct from the chromatic scale. Thus, the chromatic scale stands out as the comprehensive collection of all twelve notes within an octave.