Separation of Substances — Previous Year Questions (Class 6 Science)
Learn techniques to separate mixtures including filtration, evaporation, and magnetic separation. Understand everyday separation in practice.
TL;DR: Learn techniques to separate mixtures including filtration, evaporation, and magnetic separation. Understand everyday separation in practice.
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Learn techniques to separate mixtures including filtration, evaporation, and magnetic separation. Understand everyday separation in practice.
Separation of Substances — Previous Year Questions with Solutions
Q (2023, 2 marks): What is a mixture and a pure substance? Differentiate between them.
Answer: Pure substance: Contains only one type of particle; has definite properties and composition. Example: Distilled water, salt (NaCl).
Mixture: Contains two or more pure substances; can be separated into pure substances. Example: Salt solution, sand and salt mixture.
Q (2022, 3 marks): Describe the process of filtration. When would you use this method?
Answer: Filtration is the process of separating solids from liquids using a filter paper.
Procedure:
1. Pour the mixture into a funnel lined with filter paper
2. Solid particles are retained on filter paper
3. Liquid passes through as filtrate
Used for: Separating sand from water, separating tea leaves from tea water, removing suspended solids.
Q (2023, 4 marks): Name four methods of separation and give an example for each.
Answer: 1. Filtration: Separating sand from sugar solution
2. Evaporation: Separating salt from salt solution
3. Magnetic separation: Separating iron from iron-sand mixture using a magnet
4. Sedimentation: Allowing heavier particles to settle at the bottom
Other methods: Decantation, crystallization, distillation
Q (2022, 3 marks): How is salt obtained from sea water on a large scale?
Answer: Salt production from sea water:
1. Sea water is allowed to flow into large shallow ponds
2. The water is left to evaporate under the sun for weeks
3. As water evaporates, salt crystals are left behind
4. Salt is collected and dried further
This method is called solar evaporation.
Q (2023, 3 marks): Differentiate between evaporation and condensation. How are they related?
Answer: Evaporation: Conversion of liquid to gas. Water heats up and vaporizes.
Condensation: Conversion of gas to liquid. Water vapor cools and becomes liquid.
They are reverse processes: Evaporation + Condensation = Distillation (used to separate immiscible liquids or to purify water).
Q (2022, 2 marks): You have a mixture of iron filings and sand. How would you separate them?
Answer: Use magnetic separation:
1. Take a strong magnet
2. Slowly move the magnet over the mixture
3. Iron filings stick to the magnet
4. Sand does not stick (not magnetic)
Iron and sand are now separated.
Frequently Asked Questions
Why is distillation different from simple evaporation?
In evaporation, only the liquid vaporizes and is lost; the solute remains. In distillation, the vapor is cooled and condensed separately, allowing collection of the purified liquid. Distillation is used to separate and purify liquids or remove dissolved solids.
Can all mixtures be separated by filtration?
No, filtration works only for mixtures where one component is a solid and the other is a liquid. For salt solution (salt is dissolved), filtration won't work; you need evaporation. For mixing of two liquids, you need decantation or distillation.
More Class 6 Science PYQs
- Chemical Reactions and Equations
- Light (Reflection and Refraction)
- Electricity
- Acids, Bases and Salts
- Metals and Non-metals
- Life Processes
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