Question

say whether a statement describe a solid,a liquid or a gas.

(a) Particles move about very quickly but do not leave the surface.

Answer 1

it describes a liquid

Liquid:

• The intermolecular force of attraction present in the case of liquids is intermediate or moderate
• Due to the intermediate intermolecular force of attraction and hence moderate intermolecular space present between them, these molecules move very quickly.
• They do not have a greater amount of freedom which is seen in the case of gases so unlike gases they cannot leave the surface.

Concluding statement: Due to intermediate force of attraction and moderate intermolecular space, these molecules move quickly but do not leave the surface. Therefore, the given statement describes liquid.