Which has greater ionisation energy and why-S or P?

Explanation

P has greater ionisation energy than S. according to Hund's rule the half-filled electronic configuration is highly stable and the outermost 3p-orbital of P atom is half filled in order to produce `P^(+)` ion by removing an electron from 3p. Orbital of P requrired huge energy resulting a very high value of ionisation energy. on the other hand, S atom has partially filled 3p-orbital which attains stable half-filled electronic configuration in `S^(+)` ion. therefore, to produce S to `S^(+)` comparatively lowerr energy is required resulting a lower value of ionisation energy.