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# States of matter

Everything in the universe is made up of matter, which can exist in one of three physical states:

1. Solid
2. Liquid
3. Gas

Understanding the states of matter is fundamental to understanding the properties and behavior of materials in the world around us.

## Solid

A solid is a state of matter that has a definite shape and volume. Solids are made up of closely packed particles, which vibrate around a fixed position. The particles have a strong attraction to each other, which keeps them in a fixed position, giving the solid a definite shape.

Examples of solids include ice, wood, metal, and rock.

## Liquid

A liquid is a state of matter that has a definite volume but no fixed shape. Liquids take the shape of their container because the particles are free to move around and take on the shape of the space they occupy. The particles in a liquid are also closely packed together, but they are not fixed in position like the particles in a solid.

Examples of liquids include water, milk, juice, and oil.

## Gas

A gas is a state of matter that has neither a definite shape nor a definite volume. The particles in a gas are free to move around and fill the space they occupy completely. The particles in a gas are far apart from each other and are not held together by strong forces.

Examples of gases include oxygen, nitrogen, helium, and carbon dioxide.

## Changes in State

Matter can change from one state to another when the conditions of temperature and pressure are altered.

## The changes in state are:

Melting: When a solid is heated, it melts and becomes a liquid.

Freezing: When a liquid is cooled, it solidifies and becomes a solid.

Vaporization: When a liquid is heated, it vaporizes and becomes a gas.

Condensation: When a gas is cooled, it condenses and becomes a liquid.

Sublimation: When a solid is heated, it directly changes into a gas without passing through the liquid state.

Deposition: When a gas is cooled, it directly changes into a solid without passing through the liquid state.

Examples of changes in state include the melting of ice, the boiling of water, and the sublimation of dry ice.

The states of matter is important in many fields of science and engineering, including chemistry, physics, and materials science. It helps us to explain and predict the behavior of materials in different conditions and to design new materials with specific properties.