Which is denser, chloroform or mercury?

Density is mass per unit per volume. As a chemist you should seek out quantitative data: $\rho \left(H g\right)$ $=$ 13.55•g•mL^-1; $\rho \left(C H C {l}_{3}\right)$ $=$ 1.49•g•mL^-1. You can actually float rocks or coins on a mercury pool. Why??