Welcome to our detailed guide on Class 9 Science Chapter 1: Matter in Our Surroundings! If you’re a student preparing for your exams or a parent helping your child with their studies, this blog post is for you. We’ll dive deep into the key concepts of this chapter and provide clear, concise answers to all the important questions from the NCERT textbook. By the end of this post, you’ll have a solid understanding of matter, its states, and related phenomena—perfect for acing your Class 9 Science exams in 2025!
The Matter in Our Surroundings chapter introduces the fundamental concept of matter, its properties, and how it changes under different conditions. This forms the foundation of Chemistry in higher classes, making it crucial to grasp these basics early on. Let’s explore the chapter through its key questions and answers, ensuring you’re well-prepared for both school tests and competitive exams.
Why Study Class 9 Science Chapter 1?
Before we jump into the questions, let’s understand why this chapter matters. Everything around us—air, water, furniture, even the food we eat—is made of matter. Chapter 1 explains what matter is, how it behaves, and why it exists in different forms (solid, liquid, gas). This knowledge not only helps in exams but also builds curiosity about the world. Plus, with the current CBSE syllabus for 2025, mastering these concepts can boost your overall Science score, as this unit carries significant weight (around 23 marks out of 100).
Now, let’s get to the Class 9 Science Chapter 1 questions and answers from the NCERT textbook, covering in-text and exercise questions.
In-Text Questions and Answers: Page 3
Question 1: Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.
Answer:
Matter is anything that occupies space and has mass. From the list:
- Chair, air, almonds, cold drink, and smell of perfume are matter because they have mass and occupy space.
- Love, hate, thought, and cold are not matter—they’re feelings or sensations, not physical substances.
- Note: The smell of perfume is matter because it consists of tiny particles of the perfume dispersed in the air.
This question helps you distinguish between physical substances and abstract ideas, a key concept in understanding matter.
Question 2: Give reasons for the following observation:
The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food, you have to go close.
Answer:
The smell of food travels through the diffusion of its particles in the air. Hot sizzling food releases particles with higher kinetic energy due to the increased temperature. These particles move faster and spread out more quickly, reaching you from a distance. Cold food, however, has particles with lower kinetic energy, so they move slower and don’t diffuse as far. That’s why you need to get closer to smell it.
This showcases how temperature affects the movement of matter’s particles—an essential idea in this chapter.
Question 3: A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer:
This observation shows that matter (in this case, water) is made up of particles with spaces between them. Water, being a liquid, has particles that are loosely packed and can move past each other. When a diver cuts through, the water particles shift aside due to weak intermolecular forces, allowing the diver to pass. This highlights the fluidity and intermolecular spacing of liquids.
In-Text Questions and Answers: Page 6
Question 1: The mass per unit volume of a substance is called density (density = mass/volume). Arrange the following in order of increasing density:
Air, exhaust from chimneys, honey, water, chalk, cotton, iron.
Answer:
Density depends on how tightly particles are packed. Arranging these in increasing order:
Air < exhaust from chimneys < cotton < water < honey < chalk < iron.
- Air (gas) has the lowest density due to widely spaced particles.
- Exhaust from chimneys (also gas) is slightly denser than air.
- Cotton (solid, but porous) is less dense than liquids.
- Water (liquid) is denser than cotton but less dense than thicker liquids like honey.
- Chalk and iron (solids) have tightly packed particles, with iron being the densest.
This exercise reinforces the concept of density across states of matter.
Question 2:
(a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy, and density.
Answer:
(a) Differences in Characteristics of States of Matter:
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Definite | Indefinite (takes container shape) | Indefinite (fills container) |
| Volume | Definite | Definite | Indefinite |
| Particle Arrangement | Tightly packed, fixed | Loosely packed, mobile | Far apart, random |
| Intermolecular Force | Strong | Moderate | Weak |
| Compressibility | Negligible | Very low | High |
(b) Comments:
- Rigidity: Solids are rigid due to strong forces holding particles in fixed positions. Liquids and gases lack rigidity.
- Compressibility: Gases are highly compressible because of large spaces between particles; solids and liquids resist compression.
- Fluidity: Liquids and gases flow easily due to mobile particles; solids don’t.
- Filling a Gas Container: Gases expand to fill their container due to weak forces and high kinetic energy.
- Shape: Solids have a fixed shape; liquids adapt to their container; gases have no shape.
- Kinetic Energy: Gases have the highest kinetic energy, followed by liquids, then solids.
- Density: Solids are densest, followed by liquids, then gases (except exceptions like ice vs. water).
This question builds a comprehensive understanding of matter’s properties.
In-Text Questions and Answers: Page 9
Question 1: Why does a desert cooler cool better on a hot dry day?
Answer:
A desert cooler works by evaporating water into the air. On a hot, dry day, the air has low humidity and can absorb more water vapor. As water evaporates, it takes heat from the surroundings, cooling the air. In humid conditions, evaporation slows down, reducing the cooling effect. Hence, it cools better on hot, dry days.
Question 2: How does the water kept in an earthen pot (matka) become cool during summer?
Answer:
An earthen pot has tiny pores through which water seeps out slowly. This water evaporates, absorbing heat from the pot and the water inside, thus cooling it. This process mimics natural evaporation, keeping the water refreshing in summer.
Exercise Questions and Answers: Page 12
Question 1: Convert the following temperatures to Celsius scale:
(a) 300 K
(b) 573 K
Answer:
To convert Kelvin (K) to Celsius (°C): °C = K – 273
(a) 300 K = 300 – 273 = 27°C
(b) 573 K = 573 – 273 = 300°C
Question 2: What is the physical state of water at:
(a) 250°C
(b) 100°C
Answer:
(a) At 250°C (above boiling point of 100°C), water is in the gaseous state (steam).
(b) At 100°C (boiling point), water can be in both liquid and gaseous states, depending on whether it’s fully converted to steam.
Question 3: Why does our palm feel cold when we put some acetone or perfume on it?
Answer:
Acetone and perfume evaporate quickly when applied to the palm. During evaporation, they absorb heat from the skin, lowering its temperature and making it feel cold. This is due to the cooling effect of evaporation.
Question 4: Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Answer:
A saucer has a larger surface area than a cup. When hot tea is poured into it, the increased surface area allows faster evaporation and heat loss to the surroundings, cooling the tea quicker. This makes it easier to sip.
Question 5: What type of clothes should we wear in summer?
Answer:
We should wear light-colored cotton clothes in summer. Light colors reflect heat, keeping us cooler, while cotton absorbs sweat and allows it to evaporate, providing a cooling effect.
Tips to Master Chapter 1 for Exams
- Focus on Key Terms: Understand definitions like matter, diffusion, evaporation, and density.
- Practice Diagrams: Draw particle arrangements for solids, liquids, and gases to visualize concepts.
- Solve Numericals: Practice temperature conversions and density problems.
- Revise Regularly: Use these Q&As as a quick revision tool before exams.
In The End
Class 9 Science Chapter 1, Matter in Our Surroundings, lays the groundwork for understanding the physical world. By mastering these questions and answers, you’ll not only excel in your exams but also appreciate how matter behaves in everyday life. Whether it’s the smell of food or the cooling of water in a matka, this chapter connects science to reality.
For more study resources, check out NCERT solutions, sample papers, and revision notes online. Stay curious, keep learning, and ace your Class 9 Science exams in 2025! Let us know in the comments if you need help with any other chapter.
Class 9 Science Chapter 2: Is Matter Around Us Pure? – Questions and Answers Explained
For all Class 9 Science Chapters: Notes and Question Answers. Click Here.