Applying pressure and reducing temperature can lead to
Liquefaction of gases
Corrosion of gases
Applying pressure means forcing the atoms of matter towards each other (reducing the free space between the particles). Thus, the application of pressure reduces the inter-atomic 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, atoms of the particle will not move in random motion and will convert into liquid. As we apply pressure, interatomic distance decreases which lead to a change of state. Here applying pressure and reducing temperature leads to liquefaction of gasses, solidification of gases and solidification of liquids.