Is Sperm Impure (napak/Najas)
It is Na Pak. This is what not only human nature tells us but also the Sunnah confirms that it is na pak. The ejaculation makes the person impure, and mazi and wadi invalidate wudu, just like urination and defecation. The prophet used to wash mani at the beginning of his bath and then rub his hand on the ground and wash it to clean it.