The dissociation of weak electrolyte (a weak base or weak acid) is expressed in terms of Ostwald's dilution law. An acid is substance which furnishes a proton or accepts an electron pair, where a base is proton acceptor or electron pair donor. Stronger is acid, weaker is its conjugate base. The dissociation constants of an acid `(K_(a))` and its conjugate base `(K_(b))` are related by `K_(w)=K_(a)xxK_(b)`, where `K_(w)` is ionic product of water equal to `10^(-14) at 25^(@)C`. The numerical value of `K_(w)` however increase with temperature. In a solution of an acid or base `[H^(+)][OH^(-)]=10^(-14)`. Thus the `[H^(+)]` in a solution is expressed as: `[H^(+)]=10^(-pH)` and `pH+pOH=14`. Buffer solution are the solutions which do not show appreciable change in the pH on addition of small amount of acid or base.
The removal of `PO_(4)^(3-)` in qualitative analysis of basic radicals after II gp. is made by using a buffer solution of:

Options

A. `HCO_(3)^(-) and CO_(3)^(2-)`
B. `CH_(3)COO^(-) and CH_(3)COOH`
C. `NH_(4)^(+) and NH_(4)OH`
D. None of these

Answer

B

Explanation

`PO_(4)^(3-)` salts are soluble in weak acid medium.