Which state of matter has a fixed shape and volume?

• A. Solid
• B. Liquid
• C. Gas
• D. Plasma

Answer: (A)

Solids have a fixed shape and volume because their particles are tightly packed and vibrate in place, forming a rigid structure. This close arrangement means the material resists changes in shape and keeps the same size unless you apply a strong enough force. In contrast, liquids have a definite volume but take the shape of their container because their particles can flow past one another. Gases have neither fixed shape nor fixed volume; their particles are far apart and move freely, so they expand to fill whatever space is available. Plasma, an ionized form of matter, behaves like a highly energetic gas with no fixed shape or volume. Therefore, the state with both a fixed shape and fixed volume is solid.