States of Matter: Solid MCQs Quiz | Class 9
This Class IX Science (Code 086) quiz covers Unit I: Matter – Its Nature and Behaviour, focusing on the topic of States of Matter: Solid. The questions test your understanding of the solid state, shape, volume, rigidity, and comparative density. Attempt the quiz, submit to view your score, and download the solution PDF for revision.
Overview: The Solid State
In Class 9 Science, Unit I (Matter – Its Nature and Behaviour), we learn that matter exists in three primary states: Solid, Liquid, and Gas. The Solid State is characterized by a high degree of order among its constituent particles. Unlike liquids and gases, solids possess a fixed structure due to strong intermolecular forces.
Key Characteristics of Solids
Solids exhibit specific physical properties that distinguish them from other states of matter:
- Definite Shape and Volume: Solids maintain a fixed shape and volume. They do not flow to take the shape of a container like liquids do.
- Rigidity: Solids are rigid. This means they tend to maintain their shape when subjected to outside force. While they may break under extreme force, they resist deformation.
- Negligible Compressibility: The particles in a solid are closely packed with very little space between them, making solids difficult to compress.
- High Density: Generally, solids have higher density than liquids and gases because mass is concentrated in a smaller volume.
- Particle Motion: Particles in a solid do not move past one another; they only vibrate or oscillate about their fixed positions.
Comparison of Properties
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Intermolecular Space | Very Small | Moderate | Large |
| Force of Attraction | Strongest | Moderate | Weakest |
| Kinetic Energy | Lowest | Higher than solids | Highest |
Common Exceptions and Conceptual Clarifications
Sometimes, certain materials seem to behave differently but are still solids:
- Rubber Band: It changes shape under force but regains its original shape when the force is removed. It is considered a solid.
- Sponge: A sponge is compressible not because its particles are far apart, but because it has minute holes where air is trapped. When pressed, the air is expelled.
- Salt and Sugar: Even though they take the shape of the jar they are poured into, the individual crystals retain their fixed shape.
Extra Practice Questions
- 1. Why do solids have a fixed shape? (Answer: Strong intermolecular forces lock particles in place.)
- 2. Which state of matter has the least kinetic energy? (Answer: Solid.)
- 3. Why is ice lighter than water despite being a solid? (Answer: Ice has a cage-like structure with vacant spaces, reducing density.)
- 4. Define rigidity in the context of solids. (Answer: The property to resist change in shape under external force.)
- 5. Can diffusion occur in solids? (Answer: It is extremely slow or negligible compared to fluids.)
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