The equivalent conductance of `1 M` benzoic acid is `12.8 ohm^(-1) cm^(2)`. If the conductance of benzoate ion and `H^(+)` ion are `12` and `288.42 ohm^(-1) cm^(2)` respectively. Its degree of dissociation is :

Options

A. `39 %`
B. `3.9 %`
C. `0.35 %`
D. `0.039 %`

Answer

B

Explanation

`overset(@)(Lambda)(C_(6)H_(5)COOH) = overset(@)(Lambda)(C_(6)H_(5)COO^(-)) + overset(@)(Lambda)_((H^(+)))`
`= 42 xx 288.42 = 330.42`
`alpha = (Lambda_(m)^(C))/(overset(@)(Lambda)_(m)) = (12.8)/(330.42) = 0.0387 = 3.87%`