Molality of $30 \% \ w/w$ aqueous solution of $NaOH$ is . . . . . . . (in $m$)

What will be the molality of a solution having $18 \ g$ of glucose (mol. wt. $= 180$) dissolved in $500 \ g$ of water?

The number of moles of a solute in its solution is $20$ and the total number of moles is $80$. The mole fraction of the solute is:

$A$ 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.

An aqueous solution of urea containing $18 \ g$ of urea in $1500 \ cm^{3}$ of the solution has a density of $1.052 \ g/cm^{3}$. If the molecular weight of urea is $60$,the molality of the solution is: (in $m$)

When $5 \ g$ of acetic acid is dissolved in $1 \ L$ of ethanol,assuming no reaction occurs between them,calculate the molality of the resulting solution. (Density of ethanol = $0.789 \ g/mL$) (in $m$)