Question

The number of $P—OH$ bonds and the oxidation state of phosphorus atom in pyrophosphoric acid $(H_4{P}_2{O}_7)$ respectively are

• A. + four and three
• B. + one and four
• C. + five and four
• D. + three and one.

Answer 1

Answer: (C)

Pyrophosphoric acid : $H_4{P}_2{O}_7$

Let Oxidation state of $P$ be $x$

$\Rightarrow 4\times (+1)+2x+7\times (-2)=0$

$\Rightarrow 4+2x-14=0$

$\Rightarrow x=+5$



basicity of acid is four.