Which state of matter has a fixed shape and a fixed volume?

• A. Solids.
• B. Liquids.
• C. Gases.
• D. Plasma.

Answer: (A)

The important idea here is how shape and volume differ among the states of matter. Solids have a definite shape and a definite volume because their particles are tightly packed and held in place by strong forces, so they don’t flow to fill space or change shape easily. Liquids keep the same volume but take the shape of their container since their particles can flow past one another. Gases have neither a fixed shape nor a fixed volume because their particles move freely and spread out to fill whatever space is available. Plasma behaves like a high-energy gas with charged particles, so it also doesn’t have a fixed shape or volume under typical conditions. So, solids are the state with a fixed shape and a fixed volume.