To determine which substance is most likely the most dense at room temperature, we can look at the general densities of each of the elements listed:
- Chlorine (Cl): Chlorine is a gas at room temperature, with a density of about 0.0032 g/cm³.
- Oxygen (O): Oxygen is also a gas at room temperature, with a density of about 0.00143 g/cm³.
- Bromine (Br): Bromine is a liquid at room temperature, with a density of about 3.12 g/cm³.
- Silver (Ag): Silver is a solid at room temperature, with a density of about 10.49 g/cm³.
Comparing these densities, silver has the highest density among the substances listed.
Therefore, the substance most likely to be the most dense is silver (Ag).