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Chapter Analysis
Intermediate25 pages • EnglishQuick Summary
The chapter 'Is Matter Around Us Pure' from Class 9 Science explores the classification of matter into mixtures and pure substances. It explains homogeneous and heterogeneous mixtures, properties of solutions, suspensions, and colloids, and the concept of saturated solutions and concentration. The chapter aims to provide students with a comprehensive understanding of various types of mixtures and how they can be separated using different techniques.
Key Topics
- •Pure substances and mixtures
- •Homogeneous and heterogeneous mixtures
- •Properties of solutions, suspensions, and colloids
- •Separation techniques
- •Tyndall effect
- •Elements and compounds
Learning Objectives
- ✓Understand the difference between a pure substance and a mixture.
- ✓Explain the properties of solutions, suspensions, and colloids.
- ✓Use different separation techniques for mixtures.
- ✓Identify methods to separate components based on their physical properties.
- ✓Understand the concept of concentration and saturated solutions.
Questions in Chapter
Classify the following into elements, compounds and mixtures: Sodium, Soil, Sugar solution, Silver.
Page 25
Which of the following will show 'Tyndall effect': Salt solution, Milk, Copper sulphate solution, Starch solution?
Page 25
What is meant by a substance?
Page 19
Additional Practice Questions
Explain how you can separate a mixture of sand and salt.
mediumAnswer: To separate a mixture of sand and salt, add water to the mixture and stir. The salt will dissolve in water while the sand will not. Filter the mixture to separate the sand from the saltwater solution. Then, evaporate the water from the solution to obtain the salt.
Why is air considered a mixture?
easyAnswer: Air is considered a mixture because it contains various gases like nitrogen, oxygen, and carbon dioxide, which retain their individual properties and can be separated by physical means.
Describe the Tyndall effect and give an example where it can be observed.
mediumAnswer: The Tyndall effect is the scattering of light by particles in a colloid or in a very fine suspension. It can be observed when a beam of sunlight passes through the canopy of a dense forest, where tiny water droplets in mist scatter the light.
List three methods to separate mixtures and describe how each method works.
hardAnswer: Filtration separates solids from liquids by using a filter medium that allows only liquids to pass through. Distillation separates substances based on their boiling points by heating the mixture until one substance evaporates and then condensing it back into liquid. Chromatography separates components based on their movement through a stationary phase driven by a solvent or gas.
How can you confirm that a colorless liquid is pure water?
mediumAnswer: You can confirm the purity of a colorless liquid as water by checking for its boiling point (100°C at standard atmospheric pressure) and freezing point (0°C). It should also have no electrical conductivity if distilled and should react to form no precipitate with silver nitrate, indicating the absence of chloride ions.
NCERT Exemplar
AvailablePractice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.
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