What is the mole fraction of water in a spirit sample containing $92 \%$ ethyl alcohol by weight?

By dissolving $0.35 \, \text{mole}$ of sodium chloride in water,$1.30 \, \text{L}$ of salt solution is obtained. The molarity of the resulting solution should be reported as $..... \, \text{M}$.

Dissolving $120 \ g$ of urea (mol. wt. $60$) in $1000 \ g$ of water gave a solution of density $1.15 \ g / mL$. The molarity of the solution is (in $M$)

What is the molarity of a solution containing $3.2 \ g$ of $NaOH$ (molar mass $40 \ g \ mol^{-1}$) in $250 \ cm^{3}$ of water?

Which of the following solutions has the highest amount of solute (in grams)?

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?