Question

Which physical state is described as having a variable shape and compresses significantly?

Short answer

The physical state described is gas.

Step-by-step solution

Identify the Physical States of Matter

Matter can exist in three main physical states: solid, liquid, and gas. Each state has distinct characteristics with respect to shape, volume, and compressibility.

Examine Characteristics of a Gas

A gas has no fixed shape or volume. It adopts the shape and volume of its container. Furthermore, gases are highly compressible compared to solids and liquids.

Compare with Other States

Solids have a fixed shape and are not compressible. Liquids have a fixed volume but no fixed shape and are only slightly compressible. Gases differ by having neither a fixed volume nor a fixed shape and are significantly compressible.

Key concepts

Physical Properties of Gases

Gases are fascinating because they behave quite differently from solids and liquids. They do not have a fixed shape or volume, which means they expand to fill the space available to them.
This ability of gases to take on the shape of their containers makes them unique among the states of matter. Imagine a balloon filled with air. The air inside adopts the spherical shape of the balloon. When the balloon is untied, the gas will quickly escape and fill the surrounding space. This property allows gases to flow and spread out until they are evenly dispersed in a given volume.

• Definite volume: No, gases spread to fill their containers.
• Definite shape: No, gases take the shape of their containers.
• Particle arrangement: Far apart with lots of energy.

Because of the particles' high energy state and the significant space between them, gases flow easily, and can be compressed or expanded with ease.

Compressibility of Gases

One of the most striking features of gases is their compressibility. This is largely due to the fact that gas particles are spread out with lots of empty space between them.
When pressure is applied to a gas, these particles can be pushed much closer together. Think of compressibility like squeezing a sponge; there is room for the sponge to change shape because of the air trapped inside. In gases, this means they can be fit into smaller volumes when pressure is applied.

• Particles: Lots of space between them, allowing for compression.
• Behavior under pressure: Can be packed tightly with enough force.
• Example: Oxygen tanks, where oxygen is compressed to fit more gas into the tank's limited space.

This property is essential for various applications, such as storing natural gas or using compressed air in pneumatic tools.

Characteristics of Liquids and Solids

Liquids and solids stand in contrast to gases, offering more resistance to compression and maintaining a fixed volume.
Liquids flow and fill the shape of a container up to a certain volume. They adapt their shape but not their volume. Think of water in a glass; it takes the shape of the glass but doesn't expand or contract like gas. Solids, on the other hand, hold their shape and volume firmly, as their particles are closely packed together with little room to move.

• Solids are not compressible because their particles are tightly packed together.
• Liquids are slightly compressible due to thicker arrangement of particles compared to gases but still flow easily.
• Everyday examples include ice maintaining its shape and water adapting to cup shapes.

Both liquids and solids exhibit a level of rigidity and organization absent in gases, making them crucial for structure and stability in many processes.