Answer:
D) Measure 58.44g NaCl, dissolve it into 400ml water, and then top off to 500ml in a volumetric flask.
Explanation:
2.00M NaCl is a solution that contains 2.00 moles of NaCl per liter of solution.
As you want to prepare 500mL = 0.500L of the solution you need:
0.500L * (2.00 moles / L) = 1.00 moles of NaCl are required to prepare the solution.
Now, to convert these moles to grams you must use Molar weight (58.44g/mol) as follows:
1 moles of NaCl * (58.44g / mol) = 58.44g of NaCl are required to dissolve in 500mL to prepare the 2.00M solution.
And right option is:
D) Measure 58.44g NaCl, dissolve it into 400ml water, and then top off to 500ml in a volumetric flask.
-You can't top off a solution before dissolve all solute because it is possible the volume changes-
