Question

Match the (solution) given in List I with their characteristics in List II.

Answer 1

Option $A$ is a common example of an acidic buffer.
For option $B$, it is a mixture of two acids and hence has a $pH$ value less than $7$.
For option $C$, it is a mixture of an acid and a base with same concentration and $p{K}_a=p{K}_b$. Hence, the resulting solution formed on neutralisation is neutral and therefore has a $pH$ as $7$.
For option $D$, note that, following reaction occurs when the two components are mixed:
$C{H}_{3}COONa+HCl\to NaCl+C{H}_{3}COOH$
In the above reaction,
Moles of $HCl$ initially taken =$0.1\ast 10$=$1mmol$
Similarly, Moles of $C{H}_{3}COONa$ initially taken =$0.1\ast 300$=$30mmol$
Hence, since $C{H}_{3}COONa$ is taken in an excess, some of it ($29mmol$) remains unreacted after the reaction. Therefore, the resulting solution contains a mixture of $C{H}_{3}COOH$ and $C{H}_{3}COONa$ which is Weak acid and a Salt of its Strong Base. Hence, it forms a Buffer solution.