Calculate the mole fraction of urea in an aqueous solution of $1 \ m$ urea $(NH_2CONH_2)$.

$A$ solution of a solute in benzene has a molality of $X \ m$. If the mole fraction of the solute is $0.2$,what is the value of $X$?

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is $0.040$ (assume the density of water to be $1 \, g/mL$).

Density of $3 \ M$ $NaCl$ solution is $1.25 \ g/mL$. The molality of the solution is : (in $m$)

Calculate the mass of urea $(NH_2CONH_2)$ required in making $2.5 \, kg$ of $0.25 \, \text{molal}$ aqueous solution.

Calculate the amount of benzoic acid $(C_{6}H_{5}COOH)$ required for preparing $250 \ mL$ of $0.15 \ M$ solution in methanol.