If the ionisation constant of acetic acid is `1.8 xx 10^(-5)`, at what concentration will it be dissociated to `2%`?

Options

A. 1 M
B. 0.018 M
C. 0.18 M
D. 0.045 M

Answer

D

Explanation

For weak acid `K_(a) C alpha^(2)` or `C =K_(a) //alpha^(2)`
`=(1.8xx10^(-5))/(.02 xx 0.02)=(1.8xx10^(-5))/(4xx10^(-4))=0.045 M`