What is the definition of a solid?

What is the definition of a solid?

• A. A phase with no definite shape.
• B. A form of energy.
• C. A phase with indefinite volume.
• D. A form of matter that has a definite shape and volume.

Answer: (D)

Solids are defined by having a definite shape and volume. This happens because the particles in a solid are tightly packed and vibrate in place, which keeps the structure fixed. That fixed shape and size distinguish solids from liquids, which have a definite volume but take the shape of their container, and from gases, which have neither a fixed shape nor a fixed volume. The option describing a form of energy is not correct because solids are a state of matter, not energy. The option about an indefinite volume describes a gas, not a solid. The proper choice captures both essential traits of a solid: definite shape and definite volume.

Solids are defined by having a definite shape and volume. This happens because the particles in a solid are tightly packed and vibrate in place, which keeps the structure fixed. That fixed shape and size distinguish solids from liquids, which have a definite volume but take the shape of their container, and from gases, which have neither a fixed shape nor a fixed volume. The option describing a form of energy is not correct because solids are a state of matter, not energy. The option about an indefinite volume describes a gas, not a solid. The proper choice captures both essential traits of a solid: definite shape and definite volume.