At `25^(@)C` molar conductance of `0.1` molar aqueous solution of ammonium hydroxide is `9.54 ohm^(-1) cm^(2) mol^(-1)` and at infinte dilution its molar conductance is `238 ohm^(-1) cm^(2) mol^(-1)` The degree of ionisation of ammonium hydroxide at the same concentration and termperature is

Options

A. 0.0208
B. 0.208
C. 0.04008
D. 0.408

Answer

A

Explanation

Given moar conductance at 0.1 M concentration
`lambda_(c )=9.54 omega^(-1) cm^(2) mol^(-1)`
molar conductance at infinite dilution
`lambda_(c )^(infty) = 238 omega^(-1) cm^(2) mol^(-1)`
We know that
Degree of ionisation `alpha=(lambda_(c ))/(lambda_(c ))xx100`
`=9.54/238xx100=4.008 %`