describe how you would prepare 500.0 ml of 0.400M NaCl solution, starting from solid NaCl

Answer 1

How many mols do you want? That's M x L = ?mols.
Then mol = grams/molar mass.
I think the point of this question is how to physically describe how it is prepared. Weigh that many grams NaCl, add to a 500 mL volumetric flask, add some water, swirl until all of the NaCl is dissolved, thn add water to the mark of the volumetric flask.