Thank you for reporting, we will resolve it shortly
Q.
Which of the following has highest $pH$?
ManipalManipal 2006
Solution:
$pH$ of a solution $\propto\left[ OH ^{-}\right]$
$\frac{ M }{4} Ca ( OH )_{2}$ solution will give highest concentration of $\left[ OH ^{-}\right]$. Hence, highest $pH$.