A complex compound is represented as ${\mathrm{CoCl}}_3\cdot {\mathrm{XNH}}_3$. Its 0.1m solution in water shows depression in freezing point equal to 0.558K. Assuming 100% ionization of complex and coordination number of Co to be six, calculate the value of x? K_f for H₂O is 1.86 K Kg/mol