Applying pressure and reducing temperature can lead to:
Liquefaction of gases
Applying pressure means forcing the particles of matter towards each other (reducing the free space between the particles). Thus, the application of pressure reduces the inter-particle distance. As a result, the application of large pressure changes the gas into liquid first and then into a solid.
Reducing the temperature reduces the kinetic energy of the matter; thus, particles of the matter will not move in random motion and will convert into liquid. As we apply pressure, inter-particle distance decreases which leads to a change of state. Here applying pressure and reducing temperature leads to liquefaction of gases.