Here is the problem. I have solved the first two questions but I can't figure out #3.

Here is the problem. I have solved the first two questions but I can't figure out #3. Thank you for any help you can give!

The chemical 5-amino-2,3-dihydro-1,4-phthalazinedione, better known as luminol, is used by forensic scientists in analyzing crime scenes for the presence of washed-away blood. Luminol is so sensitive that it can detect blood that has been diluted 10,000 times. A basic solution of luminol is often sprayed onto surfaces that are suspected of containing minute amounts of blood. Luminol has a molecular weight of 177 g/mol.

1.The forensic technician at a crime scene has just prepared a luminol stock solution by adding 18.0 g

of luminol into a total volume of 75.0 mL of H2O

What is the molarity of the stock solution of luminol? 1.36M

2.Before investigating the scene, the technician must dilute the luminol solution to a concentration of 6.00×10−2 M.

The diluted solution is then placed in a spray bottle for application on the desired surfaces.

How many moles of luminol are present in 2.00 L of the diluted spray? .120 mol

3.What volume of the stock solution (Part A) would contain the number of moles present in the diluted solution (Part B)?