To find the volume ratios we say m1v1=m2v2
where m1 is the initial molarity, m2 the final molarity, v1 the initial volume, v2 the final volume.in this question m1=2.00M, m2=0.40M v2=150ml
Therefore the expression becomes: 2.00M×v1=0.40M×150mL
v1=(0.40M×150mL)/2.00M
=30mL
