Around 58*g is acceptable so long as it is accurately weighed; this is quantitatively transferred into a 1L volumetric flask. Pour in distilled water and swirl until the solute is dissolved. Then carefully fill the flask up to the 1*L graduation with more distilled water.
"Concentration" = (58.4400*g)/(58.44*g*mol^-1)xx1/(1.000*L) = ??mol*L^-1.
If I had a 250*mL volumetric flask, what mass of sodium chloride would I need in that instance?