MX₂ dissociates in M²⁺ and X^- ions in an aqueous solution, with a degree of dissociation ($$\alpha$$) of 0.5. The ratio of the observed depression of freezing point of the aqueous solution to the value of the depression of freezing point in the absence of ionic dissociation is

75.2 g of C₆H₅OH (phenol) is dissolved in a solvent of K_f = 14. If the depression in freezing point is 7 K then find the % of phenol that dimerises.