`K_(a)=4.5xx10^(-4)`

`K_(h)=K_(w)/K_(a)=(1xx10^(-14))/(4.5xx10^(-4))=1/4.5xx10^(-10)`

Let the degree of hydrolysis=h

`K_(h)=(ch^(2))/(1-h)`

`10^(10)/4.5=0.04xxh^(2)`

`:. 0.180 h^(2)=10^(-10)`

`h^(2)=10^(-10)/0.180`

`h=sqrt(5.5)xx10^(-5)=2.36xx10^(-5)`

`NaNO_(2)` is salt of `W_(A)//W_(B)`

`pK_(a)=-log(4.5xx10^(-4)=3.346~~3.35`

`log C=log 0.04=-1.39~~-1.40`

`=1/2 (pK_(w)+pK_(a)+ logC)`

`=1/2(14+3.35-1.40)=7.975`