The number of water molecule(s) directly bonded to the centre in CuSO$$_4$$ . 5H$$_2$$O is __________.

The coordination number of Al in the crystalline state of AlCl$$_3$$ is ___________.

The total number of cyclic structural as well as stereoisomers possible for a compound with the molecular formula C$$_5$$H$$_{10}$$ is ____________.

Let $$f:R \to R$$ be a continuous function which satisfies $$f(x) = \int\limits_0^x {f(t)dt} $$. Then, the value of $$f(\ln 5)$$ is ____________.