Question

Which of the following mixtures can act as a buffer if equal amount of both species is mixed?

• A. $HCN+NaCN$
• B. $HCOOH+NaOH$
• C. $N{H}_{4}OH+(N{H}_4{)}_{2}S{O}_4$
• D. (a) and (c) above.

Answer 1

The correct option is D (a) and (c) above.

Acidic buffer solution: Acidic buffer are solution of a mixture of weak acid and salt of its conjugate base of that acid with a strong base.
a) $HCN+NaCN$
Basic bufer solution: Basic buffer are solution of a mixture of weak base and salt of its conjugate acid of that base with a strong acid.
c) $N{H}_{4}OH+(N{H}_4{)}_{2}S{O}_4$
b) $HCOOH+NaOH$ is not a buffer solution.
Since formic acid is not present in excess amount.
Hence, d is correct option.