Answer
$$Volume \space percent (v/v) = 4.8 \space \% \space Br_2 \space solution$$
Work Step by Step
$$Volume \space percent (v/v) = \frac{volume \space of \space solute}{volume \space of \space solution} \times 100\%$$ $$Volume \space percent (v/v) = \frac{12 \space mL \space Br_2}{250 \space mL \space solution} \times 100\%$$ $$Volume \space percent (v/v) = 4.8 \space \% \space Br_2 \space solution$$
