`1 g` of monobasic acid in `100 g` of water lowers the freezing point by `0.168^(@)`. If `0.2 g` of same acid requires `15.1 mL mol^(-1)` of `N//10` alkali for complete neutralization, calculate the degree of dissociation of acid. `K'_(f)` for `H_(2)O` is `1.86 K mol^(-1) kg`.