Mixture vs Compound Preparation MCQs Quiz | Class 9
This Class IX Science (Code 086) quiz covers Unit I Practicals regarding the preparation of mixtures and compounds. Topics include mixing iron filings with sulphur powder, observing heterogeneous mixture properties, heating to form a homogeneous compound (FeS), and testing with magnets, carbon disulphide, and acids. Take the quiz to test your knowledge and download the PDF answer key for revision.
Overview: Mixtures vs Compounds
In this practical, students observe the difference between a physical mixture of two elements (Iron and Sulphur) and a chemical compound formed by heating them. Understanding the distinct properties of mixtures and compounds is a fundamental concept in Class 9 Chemistry.
1. Preparation of the Mixture
When iron filings (grey) and sulphur powder (yellow) are mixed together without heating, they form a heterogeneous mixture. The individual properties of iron and sulphur remain unchanged. For example, iron can still be separated by a magnet.
2. Preparation of the Compound
When the mixture of iron and sulphur is heated strongly in a china dish, a chemical reaction occurs. The mixture glows red hot, and a black mass is formed. This black mass is Iron(II) sulphide (FeS), a compound. It is homogeneous and does not show the properties of its constituents.
Comparison Table
| Property | Mixture (Fe + S) | Compound (FeS) |
|---|---|---|
| Appearance | Grey and yellow particles distinct | Black solid mass |
| Magnet Effect | Iron filings stick to magnet | No effect (Iron is chemically bonded) |
| Solvent (CS2) | Sulphur dissolves | No effect (insoluble) |
| Reaction with Acid | Evolves Hydrogen gas (H2) | Evolves Hydrogen Sulphide gas (H2S) |
Key Observations for Practical Exam
- Gas Identification: Hydrogen gas burns with a pop sound. Hydrogen Sulphide (H2S) smells like rotten eggs.
- Safety with CS2: Carbon disulphide is highly inflammable. It must be kept away from burners.
- Exothermic Reaction: The formation of FeS releases heat, causing the mixture to glow even after removing the flame.
Extra Practice Questions
- Q1: Why does the test tube glow during the heating of iron and sulphur? (Answer: The reaction is strongly exothermic).
- Q2: Can we separate iron from FeS using a magnet? (Answer: No, because iron has lost its magnetic property in the compound).
- Q3: What is the color of the residue left after dissolving the mixture in carbon disulphide? (Answer: Grey, which is the iron).
- Q4: Which gas is evolved when dilute HCl is added to the mixture? (Answer: Hydrogen).
- Q5: Is the composition of the mixture fixed? (Answer: No, mixtures have variable composition).
Content created and reviewed by the CBSE Quiz Editorial Team based on the latest NCERT textbooks and CBSE syllabus. Our goal is to help students practice concepts clearly, confidently, and exam-ready through well-structured MCQs and revision content.