Question

If an aqueous solution is very dilute, will its molality be greater than its molarity, nearly the same as its molarity, or smaller than its molarity?

Answer 1

Molality is nearly same as its molarity

because if the solution is dilute, then the density is close to 1 kg/L, the density of water. That means that for one liter of solution, you expect it to weigh one kg. That means that it doesn't matter whether you divide your moles of solute by the volume of the solution or the weight of the solution. That's why the two become the same.

PS: molarity = moles/L solvent and molality = moles/kg solvent, then if you have a very dilute solution (ie the denominator is far greater than t he numerator), the molarity and molality will both be very small and assumed equal.