Air is different from water; it has no definite volume.

Air and water are both substances that exist in different states of matter. While water is a liquid, air is a gas. These states of matter have distinct properties that differentiate them from one another. One of the key differences between air and water is that air has no definite volume.

States of matter:
- Matter is anything that has mass and occupies space.
- There are three states of matter: solid, liquid, and gas.
- Solids have a definite shape and volume, while liquids have a definite volume but no definite shape.
- Gases, on the other hand, have no definite shape or volume.

Air as a gas:
- Air is a mixture of gases, primarily nitrogen (78%) and oxygen (21%).
- As a gas, air takes the shape and volume of its container.
- This means that it does not have a definite volume or shape of its own.
- If you were to transfer air from one container to another, it would fill the new container completely, taking on its shape and volume.

Water as a liquid:
- Water, on the other hand, is a liquid at room temperature.
- Liquids have a definite volume, meaning they take up a specific amount of space.
- Water molecules are closely packed together, allowing water to maintain a fixed volume.
- Unlike gases, liquids do not expand to fill the entire container they are placed in.

Conclusion:
In conclusion, air is different from water because it is a gas and has no definite volume. It takes the shape and volume of its container, allowing it to expand and contract freely. This property of air makes it very different from water, which is a liquid with a fixed volume.