In a buffer solution containing equal concentration of `B^(-)` and `HB`, the `K_(b)` for `B^(-)` is `10^(-10)`. The `pH` of buffer solution is

Options

A. 10
B. 7
C. 6
D. 4

Answer

D

Explanation

For acidic buffer solution
`pH=pKa+log (["salt"])/(["Acid"])`
Given `[B^(-)]=[HB]`
and `K_(b)`for `B^(-)=10^(-10)`
`So K_(a)=10^(-4)` for HB
`pH=Pka=4`