What is a gas?

What is a gas?

• A. Fixed shape and volume.
• B. Definite volume but no fixed shape.
• C. No fixed shape or volume; particles move freely and have high kinetic energy.
• D. Highly dense and incompressible.

Answer: (C)

Gas is the state of matter with no fixed shape or volume. The particles are far apart and move quickly, colliding often and elastically, which means they spread to fill whatever space is available and are easy to compress. This combination—no definite shape or size, and high particle energy—is what sets a gas apart from solids and liquids. The other descriptions fit solids or liquids better, or describe something dense and incompressible, which isn’t characteristic of a gas.

Gas is the state of matter with no fixed shape or volume. The particles are far apart and move quickly, colliding often and elastically, which means they spread to fill whatever space is available and are easy to compress. This combination—no definite shape or size, and high particle energy—is what sets a gas apart from solids and liquids. The other descriptions fit solids or liquids better, or describe something dense and incompressible, which isn’t characteristic of a gas.