The dissociation constant of a substitude benzoic acid at `25^(@)C` is `1.0xx10^(-4)`. The pH of a `0.01M` solution of its sodium salt is

Options

A. 10
B. 8
C. 9
D. 7

Answer

B

Explanation

Here we are dealing with a salt of weak acid and strong base which undergoes anionic hydrolysis to give basic solution. The pH of such a solution can be calculated as (at `25^(@)C`)
`pH=7+(1)/(2)[pK_(a)+logc]`
`=7+(1)/(2)[-log 10^(-4)+log 10^(-2)]`
`= 7+(1)/(2)(4-2)`
`=7+1=8`