Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1M is `100Omega`. The conductivity of this solution is 1.29 `S m^(-1)`. Resistance of the same cell when filled with 0.2M of the same solution is `520Omega`. the molar conductivity of `0.02`M solution of the electrolyte will be

Options

A. `1.24xx10^(-4)Sm^(2)"mol"^(-1)`
B. `12.4xx10^(-4)S m^(2) "mol"^(-1)`
C. `124xx10^(-4)S m^(2)"mol"^(-1)`
D. `1240xx10^(-4)S m^(2)"mol"^(-1)`

Answer

C

Explanation

Cll constant =`x xxR`
`=1.29S m^(-1)xx100Omega=129m^(-1)`
In the 2nd case `x=("cell constant")/("Resistance")`
`=(129m^(-1))/(520Omega)= 0.248Omega^(-1)m^(-1)`
`^^_(m)=(x)/("molarity")=(0.248Omega^(-1)m^(-1))/(0.02xx10^(3)"mol"m^(-1))`
`=124xx10^(-4)Sm^(2)"mol"^(-1)`