He wanted aroma in gold to make it recognizable easily among all the metals. Well, his such an intention was to capture all the gold easily for himself.

A father being alive, the son should never die

Facing such a trauma himself, Ravana never wanted another father to face the same. He had lost his loving sons in the war against Lord Rama and was deeply hurt. Hence, he wanted to ensure that a father should never face the pain of losing his son.

Alcohol should become odorless