Question

Part

Answer 1

Answer : As per the definition of the buffer solution "It is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa".

so considering the above given condition for $CH_{3} COOH$ and $NaCH_{3}CO_{2}$ act as buffer because it satisfies and qualifies the conditions of behaving as a buffer when mixed in equal amounts,

whereas HCl and NaOH are strong acid and strong base which does not satisfies the criteria for being called as buffer.

As buffer needs a weak acid and its conjugate base to behave and act as buffer and resist any pH change.