What is the interval designation for a 2nd inversion seventh chord?

The interval designation for a 2nd inversion seventh chord is known as the 4/3 interval designation. A seventh chord consists of four notes: the root, third, fifth, and seventh. When this chord is in second inversion, the fifth of the chord is placed in the bass position, resulting in the appearance of specific intervals above that bass note.

In this case, the explanation behind the 4/3 designation stems from the structure of the chord that results from this position. The intervals above the bass (the fifth) create a 4th from the fifth to the seventh, plus the 3rd from the bass note to the root. Therefore, in second inversion, when analyzing from the perspective of the lowest note, it is established as a 4/3 relationship, corresponding to the bass note being the fifth of the chord.

Other interval designations provided do not represent the structure of a 2nd inversion seventh chord correctly. Understanding these intervals and their relationships is crucial for properly identifying chord inversions and their corresponding interval designations in music theory.