CBSE Worksheet Class 9 Chemistry Chapter 2 Is Matter Around Us Pure

Practice with CBSE Class 9 Chemistry worksheets for Chapter 2 Is Matter Around Us Pure. This CBSE worksheet for Class 9 is designed to help students practice and understand the key concepts of class 9 Chemistry chapter 2. With a focus on clarity and ease of learning, the Is Matter Around Us Pure worksheet for practice includes a variety of exercises such as fill in the blanks, questions with answers, and thought-provoking problems. Whether you’re looking for a comprehensive is matter around us pure Class 9 worksheet with answers or need a quick refresher, this resource is perfect for enhancing your understanding of mixtures, pure substances, and their properties. Get into this interactive CBSE worksheet for Class 9 Chemistry Chapter 2 and master the topic effectively.

Class 9 Chemistry Chapter 2 Is Matter Around Us Pure Overview

This chapter builds upon the foundational understanding of matter introduced in Chapter 1, focusing on the concept of purity of matter. It delves into the types of matter based on their composition and explains the classification of substances into pure and impure forms. The chapter also highlights various methods of separation used to purify substances and provides real-world applications of these concepts.

Key Concepts Covered in Class 9 Chemistry Chapter 2

Pure Substances:

• • Definition: Substances that contain only one type of particle.
  • Examples: Elements (like gold, oxygen) and compounds (like water, carbon dioxide).

Mixtures:

• • Definition: Substances made up of two or more types of particles mixed physically.
  • Types of Mixtures:
    • Homogeneous Mixtures: Uniform composition throughout (e.g., saltwater, air).
    • Heterogeneous Mixtures: Non-uniform composition (e.g., sand in water, oil and water).

Separation Techniques:

• • Methods for separating components of a mixture based on their properties:
    • Filtration: Separating insoluble solids from liquids.
    • Distillation: Purifying liquids based on differences in boiling points.
    • Chromatography: Separating and analyzing components of a mixture.
    • Centrifugation: Separating mixtures by applying centrifugal force.

Solutions, Suspensions, and Colloids:

• • Solutions: Homogeneous mixtures with particle sizes less than 1 nanometer (e.g., sugar in water).
  • Suspensions: Heterogeneous mixtures with visible particles that settle over time (e.g., sand in water).
  • Colloids: Intermediate mixtures where particles do not settle (e.g., milk, fog).

Physical and Chemical Changes:

• • Understanding how matter can change its properties:
    • Physical Change: No new substances are formed (e.g., melting, boiling).
    • Chemical Change: New substances with different properties are formed (e.g., rusting, combustion).

Elements, Compounds, and Mixtures:

• • Elements: Pure substances made of only one type of atom (e.g., hydrogen, copper).
  • Compounds: Pure substances formed by chemical combinations of two or more elements in fixed proportions (e.g., water, sodium chloride).
  • Mixtures: Physical combinations of two or more substances.

Applications and Importance:

• • Real-life examples of separating mixtures and purifying substances in industries like pharmaceuticals, food processing, and water treatment.

Is Matter Around Us Pure Class 9 Worksheet with Answers

Here are exercises from the Is Matter Around Us Pure worksheet for practice:

Section 1: Objective Questions

Q1. Fill in the blanks:

a. A mixture of two or more substances that are uniformly distributed is called a ________.
b. Common salt obtained from seawater is an example of ________.
c. The process used to separate cream from milk is ________.
d. An example of a compound is ________.

Q2. True or False:

a. A mixture always has a fixed composition.
b. Brass is a homogeneous mixture of metals.
c. Filtration is used to separate immiscible liquids.
d. Distillation is used to separate components of a mixture based on their boiling points.

Q3. Match the following:

Answers: Section 1

Q1. Fill in the blanks:

a. Solution
b. Mixture
c. Centrifugation
d. Water (or any compound, e.g., carbon dioxide)

Q2. True or False:

a. False – A mixture can have a variable composition.
b. True – Brass is a homogeneous mixture of copper and zinc.
c. False – Filtration is used to separate solids from liquids.
d. True – Distillation separates mixtures based on boiling points.

Q3. Match the following:

Section 2: Short Answer Questions

Q1. Define the following terms with examples:

a. Element
b. Compound
c. Mixture

Q2. Explain the differences between homogeneous and heterogeneous mixtures with examples.

Q3. Describe the method of separating the following mixtures:

a. Sand and water
b. Iron filings and sulfur powder

Q4. Why is air considered a mixture and not a compound?

Answers: Section 2

Q1.

• Element: A substance made up of only one type of atom. Example: Oxygen (O₂).
• Compound: A substance made up of two or more elements chemically combined in a fixed ratio. Example: Water (H₂O).
• Mixture: A combination of two or more substances that are not chemically combined. Example: Air.

Q2.

• Homogeneous mixture: Components are uniformly distributed. Example: Sugar dissolved in water.
• Heterogeneous mixture: Components are not uniformly distributed. Example: Sand mixed with salt.

Q3.

• Sand and water: Separated by filtration. Sand remains as residue, and water passes through the filter paper.
• Iron filings and sulfur powder: Separated by using a magnet, as iron is magnetic and sulfur is not.

Q4.

Air is a mixture because:

• Its components (nitrogen, oxygen, carbon dioxide, etc.) are not chemically combined.
• The composition of air can vary from place to place.
• Components of air can be separated by physical means like fractional distillation.

Section 3: Application-Based Questions

Q1. A student accidentally mixes salt and sand. Suggest a step-by-step method to separate the two and explain the principle behind each step.

Q2. Differentiate between pure substances and mixtures based on the following criteria:

a. Composition
b. Properties
c. Methods of separation

Q3. Why is the process of crystallization preferred over evaporation for purifying certain substances?

Q4. Describe a real-life situation where you can observe the process of sublimation. Name the substances involved.

Answers: Section 3

Q1.

To separate salt and sand:

1. Dissolve the mixture in water – Salt dissolves in water, but sand does not.
2. Filter the mixture – Sand remains as residue, and saltwater passes through the filter.
3. Evaporate the water – Heat the saltwater to evaporate water, leaving salt behind.
   Principle: Solubility, filtration, and evaporation.

Q2.

• Pure Substances:
  a. Fixed composition.
  b. Uniform properties throughout.
  c. Cannot be separated by physical means.
  Example: Water (H₂O).
• Mixtures:
  a. Variable composition.
  b. Properties depend on the components.
  c. Can be separated by physical means.
  Example: Air.

Q3.

Crystallization is preferred over evaporation because:

• It prevents decomposition of heat-sensitive substances.
• Impurities that remain dissolved in the solution are not crystallized.

Q4.

A real-life example of sublimation:

• Camphor or naphthalene balls: Used as a moth repellent. These substances directly change from solid to gas without becoming liquid.