A conductivity cell whose cell constant is 3.0 `cm^(-1)` is filled with 0.1 M solution of a weak acid. Its resistance is found to be 3000 `Omega`. If `wedge_(m)^(infty)= 400 Omega^(-1) cm^(2) mol^(-1)` , the degree of dissociation of the weak acid is about

Options

A. 0.015
B. 0.025
C. 0.035
D. 0.055

Answer

C

Explanation

`k=(k)/(R )=(3.0 cm^(-1))/(3000) Omega =0.04 s cm^(-1) and wedge_(m)=10 scm^(2) mol^(-1)`
Degree of dissociation `alpha =(wedge_(m))/(wedge_(m)infty)=10/400=0.025`