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A certain substance X has a normal freezing point of -6.4 C and a molal freezing...

A certain substance X has a normal freezing point of -6.4 C and a molal freezing point depression constant Kf= 3.96 degrees C.kg.mol-1. A solution is prepared by dissolving some urea ((NH2)2CO) in 950. g of X. This solution freezes at -13.6 C. calculate the mass of urea that was dissolved. Round your answer to 2 significant digits.

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