Answer:
The new volumen of the solution is 500 ml.
Step-by-step explanation:
A dilution consists of the decrease of concentration of a substance in a solution (the higher the volume of the solvent, the lower the concentration).
We use the formula for dilutions:
C1 x V1 = C2 x V2
V2= (C1xV1)/C2
V2= (400 ml x 2,5 M)/2,0M
V2= 500 ml