Answer : The pH of a saturated solution is, 12.33
Explanation : Given,
= 
First we have to calculate the solubility of
ion.
The balanced equilibrium reaction will be:

Let the solubility will be, 's'.
The concentration of
ion = s
The concentration of
ion = 2s
The expression for solubility constant for this reaction will be,
![K_{sp}=[Ca^{2+}][OH^-]^2](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BCa%5E%7B2%2B%7D%5D%5BOH%5E-%5D%5E2)
Let the solubility will be, 's'


Now put the value of
in this expression, we get the solubility.


The concentration of
ion = s = 
The concentration of
ion = 2s = 
First we have to calculate the pOH.
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)


Now we have to calculate the pH.

Therefore, the pH of a saturated solution is, 12.33