The solution which consumes `[H^(+)]` or `[OH^(-)]` or both simultaneously from externally added base in order to give negligible change in `pH`, is known as buffer solution. In general, the solution resists the change in pH. Buffer solution does not mean that there does not occur a pH change in pH. Buffer solution des not mean that there does not occur a pH change at all. It implies the pH change occurs but in neglibible amount. There are two types of buffer
(i) Acidic buffer: it is a mixture of weak acid and its salt acid strong base.
(ii) Basic buffer : It is a mixture of weak base and its salt with strong acid.
Which of the following mixture will be a buffer solution when dissolved in `500 mL` of water:

Options

A. `0.200` mol of aniline and `0.200` mol of HCl
B. `0.200` mol of aniline and `0.400` mol of `NaOH`
C. `0.200` mol of NaCl and `0.100` mol of `HCl`
D. `0.200` mol of aniline and `0.100` mol of `HCl`

Answer

D

Explanation

For the formation of Buffer solution meq of weak base `gt` meq of strong acid.