Question

Oxidation state of phosphorus in $P{O}_4^{3-},P_4{O}_{10}$ and $P_2{O}_7^{4-}$ is :

• A. +3
• B. +2
• C. -3
• D. +5

Answer 1

Answer: (D)

Oxidation number of oxygen in these compounds is $-2$. So we can find oxidation number of phosphorus.
In $P{O}_4^{3-},x+4(-2)=-3,x=+5$
In $P_4{O}_{10},4(x)+10(-2)=0,x=+5$
In $P_2{O}_7^{-2},2(x)+7(-2)=-4,x=+5$