What is the molality of a solution in which 0.42 moles aluminum chloride has been dissolved in 4200 water?

0.1 M

Explanation: Molarity refers to the concentration of a solution in moles per liter. It is calculated by dividing the number of moles of solute by the volume of solvent; Molarity = Moles of the solute : Volume of the solvent

In this case, we are given;

Number of moles of the solute, NH₄Cl as 0.42 moles Volume of the solvent, water as 4200 mL or 4.2 L

Therefore;

Molarity = 0.42 moles : 4.2 L

= 0.1 mol/L or 0.1 M

Thus, the molarity of the solution will be 0.1 M