Why can chlorine gas be liquefied relatively easily?

Chlorine gas is easily liquefied because it can be transitioned into a liquid state through relatively simple cooling or by applying pressures of only a few atmospheres at ordinary temperatures.1

The ability of gases to be liquefied is fundamentally linked to the presence of intermolecular forces, often referred to as van der Waals forces. These weak attractive forces act between molecules, allowing them to cohere and form liquids or solids under appropriate conditions of temperature and pressure. Because chlorine molecules are relatively large and polarizable compared to lighter gases, these intermolecular attractions are sufficient to facilitate condensation at moderate pressures or temperatures as high as room temperature.21