Answer: 0.4333moles/kg.
Explanation: Molality is a property of a solution and is defined as the number of moles of solute per kilogram of solvent. In the given problem the sugar is the solute and the water is the solvent, so to calculate the molality we need to divide the moles of sugar by the kilograms of water:
molality=m=moles of solute/kilograms of solvent
m=2.6moles of sugar/6kg of water
m=0.4333moles/kg.