Answer
The number of proton decays is 0.
Work Step by Step
$4.32\times 10^5L$ of water is $4.32\times 10^2m^3$ volume of water. Density of water= $1kg\hspace{2mm}m^{-3}$. Thus the pool has $4.32\times 10^2\hspace{2mm}kg $ of water. Molar mass of water=$0.018kg/mol$.
Thus the pool has $\Large \frac{4.32\times 10^2}{0.018}$ moles of water.
