The equilibrium equations and `K_(a)` values for three acids are given at `25^(@)C:`
`HA(aq)" "+" "H_(2)OhArrH_(3)O^(+)(aq)" "+" "A^(-)(aq),K_(a)=2xx10^(-5)`
`HB(aq)" "+" "H_(2)OhArrH_(3)O^(+)(aq)" "+" "B^(-)(aq),K_(a)=4xx10^(-6)`
`HC(aq)" "+" "H_(2)OhArrH_(3)O^(+)(aq)" "+" "C^(-)(aq),K_(a)=1xx10^(-4)`
The pH of 0.1 M aqueous NaC solution is (NaC is sodium salt of acid HC)

Options

A. 2.5
B. 11.5
C. 9.5
D. 8.5

Answer

D

Explanation

`pH=(1)/(2)(p_(kw)+pK_(a)+logC)`
`pH=(1)/(2)(14+4-1)`
`ph=8.5`