An aqueous solution of alcohol contains $18 \ g$ of water and $414 \ g$ of ethyl alcohol. The mole fraction of water is

$2 \ g$ of substance $A$ is added to $18 \ g$ of water to form a solution. Calculate the mass percentage of the solute. (in $\%$)

If $2.0 \ g$ of $NaOH$ is dissolved in $500 \ cm^{3}$ of water, what is the molarity of the solution?

$A$ $500 \ g$ toothpaste sample has $0.2 \ g$ fluoride concentration. What is the concentration of $F^-$ in terms of $ppm$ level?

The percentage (by weight) of sodium hydroxide in a $1.25$ molal $NaOH$ solution is (in $\%$)

The molality of a $10\%\ (v/v)$ solution of di-bromine in $CCl_4$ (carbon tetrachloride) is $x$. $x = ...... \times 10^{-2}\ m$. (Nearest integer)
[Given : molar mass of $Br_2 = 160\ g\ mol^{-1}$
atomic mass of $C = 12\ g\ mol^{-1}$
atomic mass of $Cl = 35.5\ g\ mol^{-1}$
density of dibromine $= 3.2\ g\ cm^{-3}$
density of $CCl_4 = 1.6\ g\ cm^{-3}$]