What is the freezing point of a solution prepared by adding 264g of copper(ii) sulfate to 4 liters of water? The freezing point constant of water is 1.86°C/m.

Answer 1

Note the proper way to write copper(II) sulfate with the cap i and not lower case i.
mols CuSO4 = grams/molar mass
m = mols/kg solvent. I suppose you are to assume the density of H2O is 1.00 g/mL.
Then delta T = i*Kf*m where i for CuSO4 = 2.
Finally, subtract delta T from zero C.