Question

Find the oxidation number of P in $P{H}_4^{+}$.

Answer 1

Let X be the oxidation number of P in $P{H}_4^{+}$.
The H atoms have oxidation number of +1.
$X+4(+1)=+1$
$X+4=+1$
$X=-3$
The oxidation number of P in $P{H}_4^{+}$ is $-3$.