What is observed during the depression of freezing point?

Calculate the molality of a solution if its depression in freezing point is $0.18 \ K$. $[K_f = 1.6 \ K \ kg \ mol^{-1}]$ (in $m$)

In cold countries,ethylene glycol is added to water in the radiators to:

Ethylene glycol is used as an antifreeze in cold climates. To prevent $4 \ kg$ of water from freezing at $-6^{\circ}C$,how many grams of ethylene glycol must be added? (Given for water: $K_f = 1.86 \ K \ kg \ mol^{-1}$,Molar mass of ethylene glycol $= 62 \ g \ mol^{-1}$)

$6 \ g$ urea is dissolved in $1 \ kg$ solvent. The value of $(T_1 - T_2)$ will be .......... $^\circ C$. $(K_f = 2 \ kg \ K \ mol^{-1})$

Two elements $A$ and $B$ form compounds with molecular formulas $AB_2$ and $AB_4$. When $1 \ g$ of $AB_2$ is dissolved in $20 \ g$ of $C_6H_6$,the freezing point decreases by $2.3 \ K$. When $1 \ g$ of $AB_4$ is dissolved in $20 \ g$ of $C_6H_6$,the freezing point decreases by $1.3 \ K$. The molal depression constant for benzene is $5.1 \ K \ kg \ mol^{-1}$. Calculate the atomic weights of $A$ and $B$.