When a solute is present in trace quantities,the following expression is used:

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

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 $CCl_4 = 1.6\ g\ cm^{-3}$]

Which of the following values changes with a change in temperature?

What is the molarity of acid in vinegar containing $4.0 \%$ acetic acid by $(w/w)$ and having a density of $1.02 \ g/mL$ (in $M$)?

Which of the following methods of expressing concentration are unitless?