A 0.5% (by weight) solution of `A_(2)B` in solvent C was found to freeze at `-3.25^(@)C`. Calculate the degree of dissociation of `A_(2)B` in solvent C into `A_(2)^(-)` and `B_(2)^(-)`. (Given freezing point of pure C is `-3^(@)C`, molar weight of `A_(2)B` is 60 and `K_(f)` of C is 2 `K^(-1)` "molality"^(-1)`).