molality is defined as the number of moles of solute in 1 kg of solvent
the number of moles of solute - 8.1 mol
mass of solvent - 4847 g
there are 8.1 mol in 4847 g of solvent
we need to know how many moles are in 1 kg of solvent
therefore number of moles in 1 kg of solvent is - 8.1 mol / 4.847 kg
molality of solution is - 1.67 mol/kg