Which properties are used to identify states of matter?

• A. Shape (definite or not), volume (definite or not), and particle arrangement/motion.
• B. Color, texture, and taste.
• C. Mass and temperature.
• D. Pressure and humidity.

Answer: (A)

States of matter are identified by how matter takes shape and occupies space, and by how its particles are arranged and move. A solid has a definite shape and definite volume because its particles are tightly packed and mainly vibrate in place. A liquid keeps its definite volume but adopts the shape of its container because its particles can slide past one another, giving it fluidity. A gas has neither definite shape nor definite volume; its particles are far apart and move freely, filling the space available and being easily compressible. These three properties—whether shape is definite, whether volume is definite, and how particles are arranged and move—are the best way to tell which state of matter something is in. Color, texture, and taste aren’t reliable indicators of state, and while mass, temperature, pressure, or humidity relate to conditions that can affect state, they don’t by themselves define the state.