In any prosecution for an offence under this Act which requires a culpable mental state on the part of the accused, the court shall presume the existence of such mental state but it shall be a defence for the accused to prove the fact that he had no such mental state with respect to the act charged as an offence in that prosecution.

   Explanation.—For the purposes of this section,––

   (i)  the expression “culpable mental state” includes intention, motive, knowledge of a fact, and belief in, or reason to believe, a fact;

   (ii)  a fact is said to be proved only when the court believes it to exist beyond reasonable doubt and not merely when its existence is established by a preponderance of probability.