Step-by-step explanation:
Since Ca(OH)2 is Basic, we need to find pOH:
pOH = - log [OH-]
pOH = - log(0.0001)
pOH = - ( - 4)
pOH = 4
Since, pH + pOH = 14
Therefore,
pH of 0.0001M sol. of Ca(OH)2 = 10
