What happens to the freezing point of benzene when a small quantity of naphthalene is added to it?

Find the depression in freezing point of a solution when $3.2 \ g$ of a non-volatile solute with a molar mass of $128 \ g \ mol^{-1}$ is dissolved in $80 \ g$ of solvent,given that the cryoscopic constant of the solvent is $4.8 \ K \ kg \ mol^{-1}$. (in $K$)

The freezing point of a solution containing $1.25 \ g$ of a non-electrolyte solute in $20 \ g$ of water is $271.9 \ K$. What is the molar mass of the solute? (Given: $K_f$ for water = $1.86 \ K \ kg \ mol^{-1}$,Freezing point of pure water = $273 \ K$)

$1\%$ solution of $Ca(NO_3)_2$ has a freezing point:

Arrange the following solutions in order of decreasing freezing points:
$(a) \ 0.075 \ M \ CuSO_4$ $(b) \ 0.060 \ M \ (NH_4)_2SO_4$
$(c) \ 0.14 \ M \ urea$ $(d) \ 0.04 \ M \ MgCl_2$

$50 \ g$ of antifreeze (ethylene glycol) is added to $200 \ g$ of water. What amount of ice will separate out at $-9.3 \ ^oC$? $(K_f = 1.86 \ K \ kg \ mol^{-1})$