What are the times shown??? I can help
Distillation is a technique used to separate pure liquids from a mixture of liquids by boiling the mixture to the respective boiling points of the components and selective condensation. The pure liquid separated out after the condensation of vapors is called distillate. The distillate collected is expected to be pure. The purity of the distillate can be measured by recording the boiling point of that liquid. For example, if we have water separated out it should boil at 100 otherwise it can be treated as impure.
Molality is defined as the number of moles of solute in 1 kg of solvent.
molality of solution to be prepared is 0.50 molal
this means that in 1000 g of water there should be 0.50 mol of NaCl
if 1000 g of water should contain - 0.50 mol
then 750.0 g of water requires - 0.50 mol/kg x 0.750 kg = 0.375 mol
mass of NaCl in 0.375 mol - 58.5 g/mol x 0.375 mol = 21.9 g
therefore a mass of 21.9 g of NaCl is required