What is the ratio of concentration of salt to concentration of weak acid in a buffer solution to maintain its $pH$ value at $7.2$ $(pK_{a} = 6.2)$?

The $pH$ of a buffer solution containing $0.2 \ mol/L$ $CH_3COONa$ and $1.5 \ mol/L$ $CH_3COOH$ is ($K_a$ for acetic acid is $1.8 \times 10^{-5}$).

If $50 \ mL$ of $0.2 \ M \ KOH$ is added to $40 \ mL$ of $0.5 \ M \ HCOOH,$ the $pH$ of the resulting solution is $(K_a = 1.8 \times 10^{-4})$

Assertion : Mixture of $CH_3COOH$ and $CH_3COONH_4$ is an example of acidic buffer.
Reason : Acidic buffer contains equimolar mixture of a weak acid and its salt with weak base.

Which of the following acts as a buffer solution?

$A$ buffer solution can be prepared by mixing which of the following?