Answer:
43.13mol/kg
Explanation:
since molality is the concentration of a solution in moles of solute per kilogram of solvent.
moles of Na2SO4 = mass/molar mass
= 490/142
= 3.45 mol
mass of water in kg= 80/1000
=0.08kg
molality is therefore= 3.45/0.08
=43.5mol/kg
