An aqueous solution of ethanol has density 1.025g/mL and it is 2M. What is the molality of this solution?

2M means 2 moles of ethanol in 1L of solution.
∴2 moles= 46×2=92g of ethanol.
Mass of solution= 1000×1.025=1025g
Mass of water=1025−92=933g

$\begin{array}{r}\therefore \text{ Molality }=\frac{\text{ Moles of solute }}{\text{ Mass of water in }\mathrm{kg}}\\ =\frac{2}{933}\times 1000=2.143\mathrm{M}\end{array}$