How can materials be classified on the basis of physical state?

Materials can be classified into three main groups based on their physical state: solids, liquids, and gases.

• Solids: Solids have a definite shape and definite volume. The particles in solids are closely packed and cannot move freely. Examples include iron, wood, and ice.
• Liquids: Liquids have a definite volume but do not have a definite shape. They take the shape of the container in which they are kept. The particles in liquids are less tightly packed and can move around. Water, milk, and oil are examples of liquids.
• Gases: Gases do not have a definite shape or volume. They spread out to fill the entire space available. The particles in gases are far apart and move freely. Air, oxygen, and carbon dioxide are examples of gases.

This classification helps us understand the behavior and properties of different materials in various conditions.