Buffer solutions have constant acidity and alkalinity because

Options

A. they have large excess of `H^(+)` or `OH^(-)ions`
B. they have fixed value of `pH`
C. these give unionized acid or base on reaction with added acid or alkali
D. acids and alkaliesin these solutions are shielded from attack by other ions

Answer

C

Explanation

Consider a buffer of `CH_(3)COOH+CH_(3)COONa`
Addition of acid: `H^(+)+CH_(3)COO^(-) rarr CH_(3)COOH`
Weak acid
Addition of alkali:
`underset(Weak electrolyte)(OH^(-)+CH_(3)COOH) rarr H_(2)O+CH_(3)COO^(-)`
Thus, the addition of acid or alkali does not cause any change in `pH`.