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. 0.39
B. 0.039
C. 0.0035
D. 0.00039

Answer

C

Explanation

As benzoic acid is monobasic so its equivalent conductance and molar conductance are equal.
`lambda_(C_(6)H_(5)COOH)^(@) = lambda_(C_(6)H_(5)COO^(-))^(@) + lambda_(H^(+))^(@)`
`= 42 + 288.42 = 330.42`
`12.8/330.42 = 3.9 %`