Solid vs Liquid vs Gas: The Three States of Matter Compared

The difference is only in the particles, not in new matter. In a solid the particles are held very close in an orderly pattern and can barely move, so a solid keeps its own shape and volume. In a liquid the particles are still close but can move around and slide past each other, so a liquid keeps its volume but takes the shape of the container. In a gas the particles are far apart and move fast and freely, so a gas has neither a fixed shape nor a fixed volume and fills the whole container. NCERT states this exactly in section 1.2.1.

In a solid the particles are locked in fixed positions in an orderly arrangement, so they cannot move away from each other. That is why a solid does not change shape on its own. In a gas the particles have almost no force holding them together and move quickly in every direction, so they spread out and take the shape of whatever container holds them. Same matter, different particle freedom.

Gases can be compressed the most. This is because gas particles are far apart with a lot of empty space between them, so pushing them closer is easy. In solids and liquids the particles are already very close together with little empty space, so they are almost impossible to compress. This is why you can squeeze air into a cycle tube but you cannot squeeze water or a brick.

A liquid has a fixed volume but NOT a fixed shape. The particles stay close together so the amount of space (volume) does not change, but they can slide over each other, so the liquid takes the shape of its container. So 100 mL of water is always 100 mL, but it looks different in a glass, a bottle, or a bowl. Do not mix these two up — it is a common NEET trap.

Solid: particles very close, in a regular orderly arrangement, almost no movement (only vibration). Liquid: particles close together but arranged randomly, able to move and slide. Gas: particles very far apart, random, moving fast in all directions. As you go solid to liquid to gas, the spacing between particles increases and the force holding them decreases.

Because gas particles have very weak forces between them and move fast in all directions, they keep spreading until they hit the container walls. There is nothing pulling them back together, so they occupy all the available space. This is why a small amount of perfume gas can spread across a whole room, while a solid or liquid stays where you put it.

Solids. The particles are held very close in an orderly way, so the force between them is strongest. This force is weakest in gases, where particles are far apart.

Yes. Gases are highly compressible (lots of empty space), while solids and liquids are nearly incompressible (particles already packed close). Compressibility is a quick clue in NEET questions.

Yes. All matter, whether solid, liquid or gas, has mass and occupies space. That is the definition of matter given in NCERT. Only the arrangement and movement of particles differ.

Yes. Water is the classic example: ice (solid), water (liquid) and steam (gas) are the same substance in different states. The state depends on temperature and pressure, and the states are interconvertible.

It is the foundation of Some Basic Concepts of Chemistry and states of matter. NEET often tests the difference between shape, volume and compressibility, and confuses students by mixing these properties. Getting the particle model clear here helps in gas laws and physical chemistry later.