Calculate the molarity of $NaOH$ in the solution prepared by dissolving $4 \,g$ of it in enough water to form $250 \,mL$ of the solution. (in $,M$)

$A$ sample of drinking water is severely contaminated with chloroform $(CHCl_3)$. $CHCl_3$ is considered 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.

What volume of water is to be added to $50 \, mL$ of $4 \, N$ $NaOH$ solution to obtain a $1 \, N$ solution? $(... \, mL)$

If the density of a solution is $1.17 \, g/cc$,what is the molarity of liquid $HCl$?

$A$ mixture of alcohol and water contains $54 \%$ water by mass. What is the mole fraction of ethanol?

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 ....... $M$.