5 molar solution means there are 5 moles of KCl salt in 1L. Molecular weight of KCl=74.55gmol−1 Hence, there are 5×74.55g in 1L of water Density =
mass
volume
Mass of 1L of solution =1.26g∕mL×1000‌mL = 1260 g Mass of water in solution = Mass of solution- Mass of solute =1260−372.75=887.25g Mass of water in solution =0.887kg Molality =
Number‌of‌moles‌of‌solute
Mass‌of‌solvent‌in‌kg
=
5
0.887
Molality =3.38m Hence, molality of the solution is 3.38m.