Final answer:
Lead exhibits stronger intermolecular forces at room temperature than mercury. In the case of mercury and lead, lead has a greater atomic mass than mercury, which means it has more electrons and a higher polarizability, leading to stronger dispersion forces.
Step-by-step explanation:
The substance that exhibits stronger intermolecular forces at room temperature is lead.
Larger and heavier atoms and molecules have stronger dispersion forces than smaller and lighter ones.
In the case of mercury and lead, lead has a greater atomic mass than mercury, which means it has more electrons and a higher polarizability, leading to stronger dispersion forces.