What mass of ethanol in $g$ must be added to $1.0 \, kg$ of water to have a mole fraction of ethanol equal to $0.2$?

$A$ sample of drinking water was found to be severely contaminated with chloroform,$CHCl_{3}$,supposed to be carcinogenic in nature. The level of contamination was $15 \ ppm$ (by mass).
$(i)$ Express this in percent by mass.
$(ii)$ Determine the molality of chloroform in the water sample.

Molarity is expressed as

What is the molar concentration of chloride ion in a solution made by adding $300 \ mL$ of $3.0 \ M$ $KCl$ solution to $200 \ mL$ of $4.0 \ M$ $BaCl_2$ solution? $........ \ M$

$A$ 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 $X$?

If $5.85 \ g$ of $NaCl$ is dissolved in $72 \ g$ of water,find the mole fraction of $NaCl$.