If the mole fraction of a solute in liquid naphthalene $(C_{10}H_8)$ is $0.2$,then the molality of the solution will be .............. $m$.

The normality of $10 \%$ (weight/volume) acetic acid is ......... $N$.

What would be the molality of $20\%$ (mass/mass) aqueous solution of $KI$? (Molar mass of $KI = 166 \, g \, mol^{-1}$)

$50 \ g$ of a substance is dissolved in $1 \ kg$ of water at $90^{\circ} C$. The temperature is reduced to $10^{\circ} C$. The density is increased from $1.1 \ g \ cm^{-3}$ to $1.15 \ g \ cm^{-3}$. What is the $\%$ change of molarity of the solution?

Two solutions labelled 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 $1.5 \, M$. What is the molarity of the resulting solution if they are mixed in the ratio $y : x$ by volume?

The concentration of $Ca^{2+}$ ions in a water sample is $0.0002 \ M$. What is the concentration of $Ca^{2+}$ in $ppm$ by weight-volume?