If a 2.0 mL of 3.0 M HCl is used to make a 250 mL aqueous solution, what is the molarity of the dilute solution?

To solve this we use the equation,

M1V1 = M2V2

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.

3 M x 2 mL = M2 x 250 mL

M2 = 0.024 M