The percentage of $P_2{O}_5$ in diammonium hydrogen phosphate, $\left[\right(N{H}_4{)}_{2}HP{O}_4]$ is:

The correct option is D 53.78

Molar mass of $P_2{O}_5$ is given by =

= 62 + 80

= 142g

So, percentage of $P_2{O}_5$ is

$=\frac{142\times 100}{2\times 132}$

$=\frac{142\times 100}{264}$

= 53.78%