This cannot be sensibly answered. Milliliters (mL or ml) is a measure of volume, mg is a measure of weight or mass.
2.5 ml
This cannot be sensibly answered. A milliliter (mL or ml) is a measure of volume, mg is a measure of weight or mass.
180 ml. in the metric conversion chart, ml would be the same as mg.
0.4 mg to ml
Mg is weight(milligrams) while ml is volume(millilitres), so it will depend on the density of the substance.