A substance is dissolved in water, forming a $$0.5\ \text{molar}$$ solution. If $$4.0\ \text{L}$$ of solution contains $$240\ \text{g}$$ of the substance, what is the molecular mass of the substance?

A

$$60\ \text{g/mol}$$

B

$$120\ \text{g/mol}$$

C

$$240\ \text{g/mol}$$

D

$$480\ \text{g/mol}$$