Solid — Science definition

A state of matter with a fixed shape and volume; particles vibrate in place, tightly packed.

Where it is taught

In use

Many everyday materials are described using three familiar states — solid, liquid, or gas — and the real difference between them comes down to how the tiny particles inside are arranged and how fast they're moving.

States of Matter & Phase Changes

Questions using solid

Problem 1

A heating curve shows a solid's temperature rising, then flattening out at 0°C while it melts, then rising again as a liquid. What temperature does that flat section occur at?
Answer and explanation

0 °C

The flat section on a heating curve occurs at the melting point, given here as 0°C.

Problem 2

Dry ice (solid carbon dioxide) turning directly into a gas without becoming a liquid is an example of…
  1. melting
  2. sublimation
  3. condensation
  4. freezing
Answer and explanation

sublimation

Sublimation is the direct change from solid to gas.

Problem 3

A supplied sealed-water model contains 50 g solid, then 30 g solid plus 20 g liquid, then 50 g liquid. The chemical formula remains H₂O throughout. Track mass, identity and arrangement across the three records. Explain what a particle drawing should change and what it should keep.
Answer and explanation

Each record accounts for 50 g water. Melting changes particle arrangement and freedom of movement while retaining H₂O identity. Show a larger liquid fraction through the sequence; do not enlarge individual molecules or turn them into new elements. A drawing with a handful of dots stands for many molecules and is not to scale.

Each record accounts for 50 g water. Melting changes particle arrangement and freedom of movement while retaining H₂O identity. Show a larger liquid fraction through the sequence; do not enlarge individual molecules or turn them into new elements. A drawing with a handful of dots stands for many molecules and is not to scale.

Response criteria

  • Use the supplied conditions and relevant evidence.
  • Explain the scientific mechanism or calculation.
  • State a meaningful limitation or testable next step.

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