You are supplied with HCOOH `(pK_(a)=3.74), CH_(3)COOH (pK_(a)=4.74) and NaOH ` solutions. To prepare a buffer solution of pH=3.8, which acid will you select? Give reason.

Explanation

The buffer capacity of a buffer solution consisting of a weak acid and its salt becomes maximum when pH of the buffer solutions is equal to the `pK_(a)` of the weak acid. Among the given acids, `pK_(a)` of HCOOH is very close to the desired pH of the buffer solution. hence, one should use HCOOH for prepareing the buffer.