The `P^(H)` of a buffer solution is `5`. It consists of a weak acied `HA` and its conjugate base `A^(-)`. `P^(K_(a))` of `HA` is `4.699`. Which of the following is correct combination of solutions present in the buffer solution?

Options

A. `100 mL of 0.1 M HA and 200 mL of 0.1 MA^(-)`
B. `200 mL of 0.1 M HA and 100 mL of 0.1 MA^(-)`
C. `100 mL of 0.1 M HA and 200 mL of 0.2 MA^(-)`
D. `100 mL of 0.2 M HA and 200 mL of 0.1 MA^(-)`

Answer

A

Explanation

for an acidic buffer
`:.P^(H)=P^(Ka)+"log"(["salt"])/(["acid"])`
`=54.699+"log"(["salt"])/(["acid"])`
`0.310="log"(["salt"])/(["acid"])`
`(["salt"])/(["acid"])=2`
`=(200xx0.1)/(100xx0.1)=2`