Chemistry Freezing Point Problems!! Help Please?

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1. For benzene, C6H6, the freezing point constant, Kf is 5.12 degrees C kg mol^-1 and its normal freezing point is 5.5 degrees C. What is the freezing point of a solution containing 100 g of benzene and 20 g of naphthanlene (C10H8)?

2. When 5 g of an unknown substance is dissolved in 100 g of water, the freezing point of the solution decreases by 1.5 degrees C. What is the molar mass of the unknown substance if i = 1 ( the compound doesn't dissolve to form ions in solution)?

3. If 2 moles of a substance is dissolved in 1 kg of water, the freezing point of the solution decreases by 7.44 degrees C. Does this substance dissosiate to form ions in solution?

4. Calculate the freezing point of a .2 m CaCl2 aqueous solution, assuming it dissosiates completely to form ions in solution.


Please explain!! I am so lost....Thanks!!