To a `200 ml` of `0.1 M` weak aicd `HA` solution `90 ml` of `0.1 M` solution of `NaOH` be added. Now, what volume of `0.1 M NaOH` be added into above solution so that `pH` of resulting solution be `5`. `[K_(a)(HA)=10^(-5)]`

Options

A. `2 ml`
B. `20 ml`
C. `10 ml`
D. `15 ml`

Answer

C

Explanation

`{:(,HA,+,NaOH,to,NaA,+,H_(2)O),("t=0",20,,9,,0,,0),("t=t",11,,0,,9,,0),("t=50%",10,,0,,10,,),(,10ml,,NaOH"is required.",,,,):}`