Question

Which compound among the following has the highest oxidation number of P?
$P{H}_3,H_{3}P{O}_2,PC{l}_3$ and $H_{3}P{O}_4$.

Answer 1

$H_{3}P{O}_4$ has the highest oxidation number of P.
Let X be has the oxidation number of P in $H_{3}P{O}_4$.
$3(+1)+X+4(-2)=0$
$3+X-8=0$
$X=+5$
The oxidation number of P in $H_{3}P{O}_4$ is $+5$.
The oxidation number of P in $P{H}_3,H_{3}P{O}_2,PC{l}_3$ is $-3$,
$+1$ and $+3$ respectively.