The equilibrium constants for the reaction are:
`H _(3) PO _(4) overset(K _(1)) hArr H ^(+) + H _(2) PO _(4) ^(-) , K _(1)`
`H _(2) PO _(4) ^(-) overset( K _(2)) hArr H ^(+) + HPO _(4) ^(2-) , K _(2)`
`HPO _(4) ^(2-) overset( K _(3)) hArr H ^(+) + PO _(4) ^(3-), K _(3)`
The equilibrium constant for `H _(3) PO _(4) hArr 3H ^(+) + PO _(4) ^(3-)` will be:

Options

A. `K_(1)//K_(2)K_(3)`
B. `K_(1) xx K_(2) xx K_(3)`
C. `K_(2)//K_(1)K_(3)`
D. `K_(1)+K_(2)+K_(3)`

Answer

B

Explanation

`K_(1) = ([H^(+)][H_(2)PO_(4)^(-)])/([H_(3)PO_(4)]), K_(2) = ([H^(+)][HPO_(4)^(2-)])/([H_(2)PO_(4)^(-)]), K_(3) = ([H^(+)][PO_(4)^(3-)])/([HPO_(4)^(2-)])`
Multiplying these three, `K_(1) xx K_(2) xx K_(3) = ([H^(+)]^(3)[PO_(4)^(-3)])/([H_(3)PO_(4)])`