Chemistry - Redox Reactions Question with Solution | TestHub

Oxidation state of $P$ in ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7, {\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5$ and ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_6$ is $5, 3 \& 4$ respectively 

${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7$
$2\mathrm{x}+4(+1)+7(-2)=0$
$\mathrm{x}=+5$
${\mathrm{H}}_4\underset{¯}{{\mathrm{P}}_2}{\mathrm{O}}_5$
$2\mathrm{x}+4(+1)+5(-2)=0$
$\mathrm{x}=+3$
${\mathrm{H}}_4\underset{¯}{{\mathrm{P}}_2}{\mathrm{O}}_6$
$2\mathrm{x}+4(+1)+6(-2)=0$
$\mathrm{x}=+4$