How many grams of $KCl$ would have to be dissolved in $60 \ g$ of $H_2O$ to give a $20 \%$ by weight solution?

$4 \ g$ of $NaOH$ is dissolved in $250 \ mL$ of water to prepare a solution. Find the molarity of the solution. (in $M$)

Calculate the molality of $2.5 \ g$ of ethanoic acid $(CH_{3}COOH)$ in $75 \ g$ of benzene.

The molarity of the solution obtained by mixing $750 \ mL$ of $0.5 \ (N) \ HCl$ with $250 \ mL$ of $2 \ (M) \ HCl$ is ........... $M$.

What is the relation between molality $(m)$ of the solution and molar mass $(M_2)$ of the solute,where $W_2$ is the mass of solute in grams and $W_1$ is the mass of solvent in grams?

Calculate the mole fraction of $C_2H_6O_2$ (ethylene glycol) in an aqueous solution containing $28 \%$ by mass of $C_2H_6O_2$.