Is contrary motion a requirement when approaching a cadence?

1. What harmonic motion is required for an authentic cadence?
2. What is contrary motion in music theory?
3. Are unequal fifths allowed?

What harmonic motion is required for an authentic cadence?

Authentic cadences (they sound conclusive!)

An authentic cadence occurs when the harmonic progression V–I (or V–i in minor) marks the end of a phrase. There are two kinds of authentic cadence: A perfect authentic cadence (PAC) occurs when both of the following conditions are met (Example 2, m. 8):

What is contrary motion in music theory?

Contrary motion is motion in opposite directions. That is, when one of the lines moves up, the other line moves down (that is, in inversion). ... Contrary motion is important to maintain the independence of the melodic movement in contrapuntal writing.

Are unequal fifths allowed?

The reverse, a rising P5→d5, is acceptable voice leading (no deduction). Unequal fifths in either order, when descending, are acceptable (no deduction).