To solve this we use the dilution equation used in chemistry,
M1 V1 = M2 V2
where M1 is the concentration of the stock solution, V1 is the
volume of the stock solution, M2 is the concentration of the new solution and
V2 is its volume.
M1 V1 = M2 V2
1.25 M x V1 = 0.500 M x 180 mL
V1 =72 mL of the concentrated solution
Therefore, the correct answer would be option C.
