Matter In Our Surroundings Class 9 Sample Paper With Answers

Matter In Our Surroundings Class 9 Sample Paper With Answers: “Matter in Our Surroundings” is a fundamental topic in the field of science that serves as a stepping stone for understanding the nature and properties of matter.

Addressed in the curriculum of Class 9, this subject delves into the intriguing world of materials that make up our environment – from the air we breathe to the substances that compose everyday objects.

Exploring the diverse states of matter, including solids, liquids, and gases, as well as the underlying principles of physical changes such as evaporation, condensation, and sublimation, this study is pivotal in comprehending the behavior and transformations of matter.

Through this exploration, students are introduced to the microscopic realm of particles, helping them grasp the essence of kinetic theory and its application to various real-world scenarios.

The study of “Matter in Our Surroundings” not only nurtures scientific curiosity but also forms the foundation for more advanced concepts in chemistry and physics, making it an integral and captivating component of the Class 9 curriculum.

In this article, we going to discuss Matter In Our Surroundings Class 9 Sample Paper With Answers. This will help you in your exam preparation.

Table of Contents

Matter In Our Surroundings Class 9 Sample Paper With Answers (Q 1 – Q 10)

1. Why do we see water droplets collected on the outer surface of a glass container containing ice?

The water droplets form due to condensation. When the cold surface of the glass container comes into contact with the warmer air, the air’s moisture condenses into liquid water droplets on the glass’s outer surface.

2. Explain why solids have a fixed shape but liquids and gases do not have a fixed shape.

Solids have a fixed shape because their particles are tightly packed and held in a fixed arrangement by strong forces of attraction. In liquids and gases, particles have more freedom of movement and weaker intermolecular forces, allowing them to flow and take the shape of their container.

3. Why is it advisable to use a pressure cooker at higher altitudes?

At higher altitudes, atmospheric pressure is lower, causing water to boil at a lower temperature. Using a pressure cooker increases the cooking temperature and helps food cook faster despite the lower boiling point.

4. What are fluids?

Fluids are substances that can flow and do not have a fixed shape. They include both liquids and gases.

5. Why is water a liquid at room temperature?

Water is a liquid at room temperature due to its intermolecular forces. Although its molecules can move freely, they still have enough attraction to maintain a liquid state at typical room temperatures.

6. Cotton is solid but it floats on water. Why?

Cotton’s low density and structure with air pockets make it less dense than water, causing it to float. The air trapped within the fibers adds buoyancy.

7. Why are solids generally denser than liquids and gases?

Solids have particles closely packed in a regular arrangement, leading to higher density. In liquids and gases, particles have more space between them, resulting in lower density.

8. Name the factors that affect evaporation.

Factors affecting evaporation include temperature, surface area, humidity, and wind speed. Higher temperature, larger surface area, lower humidity, and higher wind speed accelerate evaporation.

9. How is the high compressibility property of gas useful to us?

The high compressibility of gases allows them to be easily compressed into smaller volumes. This property is utilized in applications like inflating tires, airbags, and gas storage tanks.

10. With the help of an example, explain how the diffusion of gases in water is essential?

Oxygen dissolves in water, allowing aquatic organisms to respire. For instance, fish extract dissolved oxygen from water through their gills for respiration.

Matter In Our Surroundings Class 9 Sample Paper With Answers (Q 11 – Q 20)

11. On a hot sunny day, why do people sprinkle water on the roof or open ground?

Sprinkling water increases humidity and cools the surroundings through the process of evaporation, providing relief from the heat.

12. Why do people perspire a lot on a hot humid day?

Humid conditions slow down evaporation, causing the body’s sweat to linger on the skin. This leads to a feeling of increased perspiration, even if the body is not actually producing more sweat.

13. A balloon when kept in the sun bursts after some time. Why?

The sun’s heat causes the air inside the balloon to expand, increasing the pressure. If the pressure becomes too high, it can exceed the balloon’s strength, causing it to burst.

14. Pressure and temperature determine the state of a substance. Explain this in detail.

Pressure and temperature affect the intermolecular forces and motion of particles. At higher temperatures, particles move more and can overcome forces to change states. Higher pressure can compress gases into liquids or solids.

15. Explain, giving examples, the various factors on which the rate of evaporation depends.

The rate of evaporation depends on temperature (higher temperature leads to faster evaporation), surface area (larger area increases the rate), humidity (lower humidity increases the rate), and air movement (wind enhances evaporation). For example, wet clothes dry faster on a hot, windy day than on a cool, humid day.

16. What is matter?

Matter is anything that occupies space and has mass. It is composed of tiny particles called atoms and molecules.

17. What are the three states of matter?

The three states of matter are solids, liquids, and gases.

18. Define evaporation and give an example.

Evaporation is the process by which a liquid changes into a vapor or gas at temperatures below its boiling point. An example is water evaporating from a wet clothesline.

19. What is sublimation?

Sublimation is the process in which a solid directly changes into a gas without passing through the liquid state. Dry ice (solid carbon dioxide) is an example of sublimation.

20. Explain the concept of the boiling point.

The boiling point is the temperature at which a liquid changes into a gas throughout the bulk of the liquid. At this temperature, the vapor pressure of the liquid equals the atmospheric pressure.

Matter In Our Surroundings Class 9 Sample Paper With Answers (Q 21 – Q 27)

21. What is the difference between a physical change and a chemical change?

In a physical change, the substance’s identity remains the same even though its appearance may change. In a chemical change, new substances with different properties are formed.

22. Define diffusion. Answer:

Diffusion is the process of movement of particles from an area of higher concentration to an area of lower concentration, resulting in their even distribution.

23. Explain the concept of the kinetic theory of matter.

The kinetic theory states that all matter consists of tiny particles (atoms or molecules) in constant motion. The temperature of a substance is related to the average kinetic energy of its particles.

24. Why do gases exert pressure on their containers?

Gas particles are in constant random motion. When they collide with the walls of their container, they exert pressure.

25. How does increasing the temperature affect the rate of evaporation?

Increasing the temperature increases the kinetic energy of particles, leading to more rapid movement and more frequent escape from the liquid’s surface, thus increasing the rate of evaporation.

26. What is humidity?

Humidity refers to the amount of water vapor present in the air.

27. Why do solids have a definite shape and volume?

In solids, the particles are closely packed and held in a fixed position by strong intermolecular forces, which is why they have a definite shape and volume.

Long Type of Questions on Matter In Our Surroundings Class 9 Sample Paper With Answers

Q 1. Explain the difference between physical change and chemical change.

Certainly, here’s a concise explanation of the difference between physical change and chemical change:

Physical Change:
A physical change is a transformation in which the substance’s state, appearance, or form alters without changing its chemical composition. During a physical change, the substance’s molecules or atoms reorganize themselves, but the fundamental nature of the substance remains the same.

Examples:
– Melting ice to form water: The molecules of water remain the same; only the arrangement changes from a solid to a liquid state.
– Cutting a piece of paper: The paper’s composition remains unchanged; it’s just broken into smaller pieces.

Chemical Change:
A chemical change, also called a chemical reaction, results in the formation of new substances with different chemical compositions and properties. During a chemical change, the bonds between atoms or molecules are broken and rearranged to create entirely new substances.

Examples:
– Burning wood: Wood reacts with oxygen to produce carbon dioxide, water, and ash. The original wood is chemically transformed into these new substances.
– Rusting of iron: Iron reacts with oxygen and moisture to form iron oxide (rust), altering the chemical composition of the iron.

In summary, physical changes involve alterations in the physical properties of a substance, such as state or appearance, while the substance’s chemical composition remains unchanged. Chemical changes involve the creation of new substances with different properties due to the rearrangement of atoms or molecules, resulting in a change in chemical composition.

Q 2. Discuss the process of sublimation with relevant examples.

Sublimation is the process in which a substance transitions directly from its solid state to its gaseous state without passing through the liquid state. This occurs when the vapor pressure of the solid becomes equal to the atmospheric pressure. Sublimation is less common than other phase changes like melting, freezing, evaporation, or condensation, but it’s still an important phenomenon with various practical applications.

Examples of Sublimation:

1. Dry Ice (Solid Carbon Dioxide): Dry ice is a well-known example of sublimation. At normal atmospheric pressure, dry ice sublimes directly from a solid to a gas at around -78.5°C (-109.3°F). It’s often used in theatrical fog effects and to preserve frozen foods.

2. Naphthalene Balls: Naphthalene balls, often used as moth repellents, exhibit sublimation. Over time, they gradually evaporate without leaving a liquid residue, as they undergo sublimation from solid to gas.

3. Iodine: Iodine crystals can sublime at room temperature. When exposed to air, solid iodine slowly changes into a purple vapor, bypassing the liquid state. This property is used to demonstrate sublimation in laboratory experiments.

4. Camphor: Camphor is another substance that sublimes. Solid camphor gradually transforms into a vapor, releasing its characteristic odor. This property is utilized in traditional practices and rituals.

5. Freeze-Drying: In the food industry, freeze-drying is a process that involves freezing a substance and then sublimating the frozen water content, leaving behind a dry product. This method is used to preserve the flavor and nutritional value of various foods.

6. High-Altitude Snow and Ice: In regions with high altitudes and low atmospheric pressure, snow and ice can undergo sublimation directly into water vapor without melting into liquid water first.

In summary, sublimation is the phase transition from a solid directly to a gas without passing through the liquid state. This process is exhibited by various substances, including dry ice, naphthalene, iodine, and camphor, and it has practical applications in industries such as food preservation and laboratory techniques.

Q 3. What is the critical temperature and critical pressure of a substance?

The critical temperature and critical pressure are specific thermodynamic properties of a substance that mark the conditions at which the substance transitions from its gas phase to its liquid phase without any distinction between the two phases. These properties are important in understanding a substance’s behavior under extreme conditions.

Critical Temperature (Tc): The critical temperature is the highest temperature at which a substance can exist in its liquid state, regardless of the pressure applied. Above this temperature, no amount of pressure will cause the substance to liquefy; it will remain in the gaseous state. It is essentially the temperature beyond which the distinction between gas and liquid phases disappears.
Critical Pressure (Pc): The critical pressure is the minimum pressure required to liquefy a substance at its critical temperature. Below the critical pressure, the substance cannot be liquefied, no matter how low the temperature is.

These critical properties are often depicted on a phase diagram, which is a graph that shows the relationships between temperature, pressure, and the different phases (solid, liquid, and gas) of a substance. The critical point is the specific point on the phase diagram where the critical temperature and critical pressure intersect.

For example, water’s critical temperature is approximately 374°C (647.1°F), and its critical pressure is about 218 atmospheres. This means that if you were to try to liquefy water at temperatures above 374°C (no matter how high the pressure), or if you were to try to pressurize water at pressures below 218 atmospheres (no matter how low the temperature), it would remain in the gas phase.

Understanding the critical temperature and critical pressure of a substance is important in various scientific and industrial applications, such as in the design of supercritical fluid extraction processes and in predicting the behavior of substances at extreme conditions.

Read Also

Importance of Matter In Our Surroundings Class 9 Sample Paper With Answers

Following are the benefits of Matter In Our Surroundings Class 9 Sample Paper With Answers

Familiarity with Exam Format: Sample papers expose students to the format and types of questions they might encounter in exams, reducing anxiety and improving confidence.
Concept Clarity: By attempting sample papers and comparing their answers with the provided solutions, students can identify areas where their understanding might be lacking and seek further clarification.
Application of Knowledge: Sample papers require students to apply their knowledge to specific scenarios and problems, helping them practice critical thinking and problem-solving skills.
Time Management: Sample papers help students practice time management during exams by providing a simulated exam environment where they need to allocate time for each question.
Self-Assessment: After attempting sample papers, students can assess their own performance by comparing their answers with the provided solutions. This self-assessment helps them understand their strengths and weaknesses.
Targeted Revision: Based on their performance on sample papers, students can focus their revision on areas where they need improvement.
Confidence Building: Successfully completing sample papers can boost students’ confidence and reduce exam-related stress, as they have already practiced similar questions.
Holistic Learning: Sample papers cover various aspects of the topic, promoting a well-rounded understanding of “Matter in Our Surroundings.”

Frequently Asked Questions – FAQs

What are the three states of matter, and how do they differ from each other?

The three states of matter are solids, liquids, and gases. Solids have a definite shape and volume, liquids have a definite volume but take the shape of their container, and gases have neither a definite shape nor volume.

How does evaporation occur, and what factors influence the rate of evaporation?

Evaporation occurs when the particles at the surface of a liquid gain enough energy to escape into the gas phase. Factors affecting the rate of evaporation include temperature, surface area, humidity, and wind speed.

Explain sublimation with examples. How is sublimation different from evaporation?

Sublimation is the direct transformation of a solid into a gas without passing through the liquid phase. Examples include dry ice and naphthalene balls. Unlike evaporation, which occurs only at the surface, sublimation involves the entire solid transforming into a gas.

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