Suspension Preparation MCQs Quiz | Class 9
This Class IX Science (Code 086) quiz covers Unit I: Practicals, specifically focusing on the preparation of suspensions using soil, chalk powder, and fine sand in water. Test your understanding of their properties, stability, and observations. Click ‘Submit Quiz’ to check your score and ‘Download Answer PDF’ to save your results.
Understanding Suspensions in the Laboratory
A suspension is a heterogeneous mixture containing solid particles large enough for sedimentation. In the Class 9 practical syllabus, students prepare suspensions using materials like soil, chalk powder, and fine sand mixed with water. Unlike true solutions, the particles in a suspension do not dissolve but remain suspended throughout the bulk of the medium for some time.
Key Observations
When preparing these mixtures, several distinct properties are observed:
- Turbidity: The mixture appears cloudy or opaque immediately after stirring. Light cannot pass through it clearly.
- Instability: If left undisturbed, the heavier solute particles (sand, chalk, soil) settle down at the bottom due to gravity. This confirms the mixture is unstable.
- Filtration: Because the particles are larger than 100 nm, they cannot pass through filter paper. A residue is left behind on the paper, and the filtrate is usually clear water.
Comparison: True Solution vs. Suspension
| Property | True Solution (e.g., Salt + Water) | Suspension (e.g., Chalk + Water) |
|---|---|---|
| Nature | Homogeneous | Heterogeneous |
| Visibility | Particles invisible | Particles visible to naked eye |
| Stability | Stable (does not settle) | Unstable (settles on standing) |
| Tyndall Effect | No scattering of light | Scatters light (Tyndall effect) |
Quick Revision Notes
- Soil in Water: Forms a muddy suspension; heavier sand particles settle first, followed by finer clay particles.
- Chalk Powder in Water: Forms a white, opaque suspension. The chalk settles slowly compared to sand.
- Fine Sand in Water: Settles very quickly because sand particles are relatively large and heavy.
- Transparency: All these mixtures are opaque or translucent, never transparent.
Extra Practice Questions
- Why is a suspension called a heterogeneous mixture?
- What happens when a beam of light is passed through a suspension of chalk powder?
- Differentiate between the residue obtained from filtering muddy water versus salt water.
- Why do we say suspensions are unstable?
- Can the components of a suspension be separated by simple physical methods? Name one.
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