Answer:
18.75 mL
Step-by-step explanation:
We must apply the dilute factor formula to solve this:
Diluted volume . Diluted M = Concentrated volume . concentrated M
250 mL . 0.15 M = Concentrated volume . 2 M
(250 mL . 0.15 M) / 2M = Concentrated volume
18.75 mL = Concentrated volume