Which relations are not correct for an aqueous dilute solution of `K_(3)PO_(4)` if its degree of dissociation is `alpha`?

Options

A. `DeltaP/P^(@)=(Molalityxx18xx(1+3alpha))/1000`
B. `DeltaP/P^(@)=(pi_(obs)xx18xx(1+3alpha))/(RT xx 1000)`
C. `DeltaP/P^(@)=(DeltaT_(f)_(obs)xx18)/(K_(f) xx 1000)`
D. Mw of `K_(3)PO_(4))=Mw_(obs)xx(1+3alpha)`

Answer

A, C, D

Explanation

`DeltaP/P^(@)=n_(2)/n_(1)=(n_(2) xx Mw_(1) xx 1000)/(W_(1) xx 1000)=("Molality" xx Mw_(1))/1000`
For electrolyte `(DeltaP)/P^(@)=(Molality xx M)/(1000) xx (1 + 3alpha)`
`(Mw_(1)=18 "for" H_(2)O)`
also, `pi_(obs)=C xx R xxT (1 + 3alpha)`
`:.DeltaP/P^(@)=(pi_(obs))/(RT) xx 18/1000`
`DeltaT_(f obs)=K_(f) xx "molality" xx (1+ 3alpha)`
`(DeltaP)/P^(@)=(DeltaT_(f obs) xx 18)/(K_(f) xx 100)`
`i=(1 + 3alpha)="Calculated molecular weight"/"Observed molecular weight"`
Therefore, molecular weight of `K_(3)PO_(4)=M_(obs) xx (1 + 3alpha)`