Answer: There are 0.558 liters of the stock solution would she need to have 97.9 grams NaCl.
Step-by-step explanation:
Given: Molarity = 3.0 M
Mass of NaCl = 97.9 g
Molar mass of NaCl = 58.44 g/mol
As number of moles is the mass of substance divided by its molar mass.
So, moles of NaCl are calculated as follows.

Molarity is the number of moles of a substance present in liter of a solution.
Therefore, volume of given solution is calculated as follows.

Thus, we can conclude that there are 0.558 liters of the stock solution would she need to have 97.9 grams NaCl.