Which form of matter retains a fixed shape and volume under standard conditions?

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

Answer: (B)

A solid has a definite shape and fixed volume under standard conditions because its particles are tightly packed and vibrate in place rather than flowing. This strong arrangement gives a stable, rigid structure that doesn’t change shape on its own and resists compression. In comparison, liquids have a definite volume but take the shape of their container since their particles flow past each other, while gases fill the space available and have neither fixed shape nor fixed volume. Plasma behaves more like an energized gas and doesn’t maintain a fixed shape or volume at standard conditions. So, the form that retains both fixed shape and fixed volume is solid.