Calculate the $\% \, w/w$ of a solution formed by dissolving $20 \, g$ of solute in $200 \, g$ of water.

Which of the following is incorrect for the mole fraction $(x)$?

Two solutions labeled as $3\,M\,HCl$ and $1\,M\,HCl$ are mixed in the ratio of $x : y$ by volume and the molarity of the resulting solution is $1.5\,M$. The molarity of the resulting solution if they are mixed in the ratio $y : x$ by volume is ....... $M$.

$A$ sample of drinking water was found to be severely contaminated with chloroform $(CHCl_{3})$,supposed to be a carcinogen. 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.

$25 \ g$ of a solute of molar mass $250 \ g \ mol^{-1}$ is dissolved in $100 \ mL$ of water to obtain a solution whose density is $1.25 \ g \ mL^{-1}$. The molarity and molality of the solution are respectively

What is the mole fraction of water in a spirit sample containing $92\%$ ethyl alcohol by mass?