Mixture vs Compound: Magnet Test MCQs Quiz | Class 9
Test your understanding of the Class IX Science (Code 086) Practicals (Unit I) regarding the topic “Mixture vs Compound” with a specific focus on Magnetic separation behavior. This quiz covers the observation of iron filings and sulphur powder before and after heating. Submit your answers to view the detailed scorecard and download the PDF answer sheet.
Overview: Mixture vs Compound
In Class 9 Science Practicals (Unit I), students distinguish between a mixture of iron filings and sulphur powder versus the compound formed by heating them (Iron Sulphide, FeS). A key method to distinguish these two is the Magnet Test, which relies on the magnetic properties of iron.
The Magnet Test Experiment
When a magnet is brought near the materials, the behavior differs significantly based on whether the components are chemically bonded or just physically mixed.
| Property | Mixture (Iron + Sulphur) | Compound (Iron Sulphide) |
|---|---|---|
| Magnetic Behavior | Iron filings are attracted to the magnet. Sulphur remains behind. | No attraction (Iron loses its magnetic property in the compound). |
| Separation | Physical separation is possible. | Physical separation is not possible. |
| Composition | Heterogeneous (particles visible). | Homogeneous (uniform black mass). |
Key Observations
- Mixture: The greyish-black iron particles cling to the magnet, leaving yellow sulphur powder behind. This proves that constituents in a mixture retain their individual properties.
- Compound: The black mass of FeS does not show attraction to the magnet because a chemical reaction has occurred, forming a new substance with new properties.
Quick Revision Notes
- Physical Change: Mixing iron and sulphur is a physical change; no new substance is formed.
- Chemical Change: Heating the mixture forms Iron Sulphide (FeS), which is a chemical change.
- Principle: Magnetic separation works only when one component is magnetic and the other is not, and they are not chemically bonded.
Extra Practice Questions
1. Why does carbon disulphide dissolve sulphur but not iron? (Solubility property)
2. What gas is evolved when dilute HCl is added to the mixture? (Hydrogen gas)
3. What gas is evolved when dilute HCl is added to the compound FeS? (Hydrogen Sulphide gas)
4. What is the color of the Iron and Sulphur mixture? (Grey-Yellow)
5. Does heating the mixture always result in a compound? (Only if heated to reaction temperature)
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