1) solids turning into liquids
answer- melting
the particles of the solid gain kinetic energy and start to vibrate more, so their bonds become looser (liquid)
2) solids turning into gases
answer- sublimation
it is caused by the absorption of heat, which provides enough energy to overcome the attractive forces and become a gas. It requires additional energy (so it is an endothermic change)
3) gases turning into liquids
answer- condensation
gases lose kinetic energy as the temperature decreases, so particles come together to form a liquid
4) liquids turning into solids
answer- freezing
again, particles lose kinetic energy and slow down, which causes them to get stronger attractive forces to form a solid
hope this helps!