When 0.4 g CH\(_3\)COOH is added to 40 g of Benzene to form a solution, the freezing point is depressed by 0.45°C. If Acetic acid undergoes dimerisation in Benzene (K\(_f\) = 5.12 K kg/mol), what is the percentage association of the acid in Benzene?
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For calculating the percentage association, always consider the impact of dimerisation or other molecular interactions on the molality and freezing point depression.