Matter in Our Surroundings is an important topic covered in Class 9 Science. This topic deals with the basic concepts of matter, including its properties, states, and changes. Taking good notes for this topic is essential for a better understanding of the material covered in the class. In this blog post, we will be discussing Matter in Our Surroundings Class 9 Notes, and how to take effective notes for this topic.
Table of Contents
Page No: 3
1. Which of the following are matter? Chair, air, love, smell, hate, almonds, thought, cold, lemon water, smell of perfume.
Answer: Anything that occupies space and has mass is called matter.
Matter can exist in three physical states – solid, liquid, and gaseous.
Chair and almond are forms of matter in the solid state, cold drink is a liquid state of matter and air is a gaseous state of matter.
2. Give reasons for the following observation:
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
Answer: Solids diffuse at a very slow rate. But, if the temperature of the solid is increased, then the rate of diffusion of the solid particles into air increases. This is due to an increase in the kinetic energy of solid particles. Hence, the smell of hot sizzling food reaches us even at a distance, but to get the smell from cold food we have to go close.
3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer: The ability of a diver to cut through water in a swimming pool shows that the particles of matter have intermolecular spaces. The intermolecular spaces in liquids is fair enough to let the diver pass through it.
4. What are the characteristics of the particles of matter?
Answer: The characteristics of particles of matter are:
- Particles of matter have spaces between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
Page No: 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 chimney, honey. water, chalk, cotton, and iron.
Answer: The given substances in the increasing order of their densities can be represented as:
Air < Exhaust from chimney < Cotton < Water < Honey < Chalk < Iron.
Question 2: (a) Tabulate the differences in the characteristics of states of matter.
Answer:
| Solid state | Liquid state | Gaseous state |
|---|---|---|
| Definite shape and volume. | No definite shape. Liquids attain the shape of the vessel in which they are kept. | Gases have neither a definite shape nor a definite volume. |
| Incompressible. | Compressible to a small extent. | Highly compressible. |
| There is little space between the particles of a solid. | These particles have a greater space between them. | The space between gas particles is the greatest. |
| These particles attract each other very strongly. | The force of attraction between liquid particles is less than solid particles. | The force of attraction is least between gaseous particles. |
| Particles of solid cannot move freely. | These particles move freely. | Gaseous particles are in a continuous, random motion. |
(b) Comment upon the following:
Rigidity: Rigidity can be expressed as the tendency of matter to resist a change in shape.
Compressibility: Compressibility is the ability to be reduced to a lower volume when force is applied.
Fluidity: Fluidity is the ability to flow.
Filling a gas container: By filling a gas container we mean the attainment of shape of the container by gas.
Shape: Shape defines a definite boundary.
Kinetic energy: Kinetic energy is the energy possessed by a particle due to its motion.
Density: Density is mass per unit volume.
Question 3: Give reasons:
(a) A gas fills completely the vessel in which it is kept.
Answer: There is little attraction between particles of gas. Thus, gas particles move freely in all directions. Therefore, gas completely fills the vessel in which it is kept.
(b) A gas exerts pressure on the walls of the container.
Answer: Particles of gas move randomly in all directions at high speed. As a result, the particles hit each other and also hit the walls of the container with a force. Therefore, gas exerts pressure on the walls of the container.
(c) A wooden table should be called a solid.
Answer: A wooden table has a definite shape and volume. It is very rigid and cannot be compressed i.e., it has the characteristics of a solid. Hence, a wooden table should be called a solid.
(d) We can easily move our hand in air, but to do the same through a solid block of wood, we need a karate expert.
Answer: Particles of air have large spaces between them. On the other hand, wood has little space between its particles. Also, it is rigid. For this reason, we can easily move our hands in air, but to do the same through a solid block of wood, we need a karate expert.
Question 4: Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
Answer: The mass per unit volume of a substance is called density (density = mass/volume). As the volume of a substance increases, its density decreases. Though ice is a solid, it has large number of empty spaces between its particles. These spaces are larger as compared to the spaces present between the particles of water. Thus, the volume of ice is greater than that of water. Hence, the density of ice is less than that of water. A substance with lower density than water can float on water. Therefore, ice floats on water.
Page No: 9
Question 1: Convert the following temperature to Celsius scale:
(a) 300K
Answer: 300 K (300-273) ° C = 27° C
(b) 573K
Answer: 573 K = (573-273) C = 300°C
Question 2: What is the physical state of water at:
(a) 250°C
Answer: Water at 250° C exists in gaseous state.
(b) 100°C
Answer: At 100° C, water can exist in both liquid and gaseous form. At this temperature, after getting the heat equal to the latent heat of vaporization, water starts changing from liquid state to gaseous state.
Question 3: For any substance, why does the temperature remain constant during the change of state?
Answer: During a change of state, the temperature remains constant. This is because all the heat supplied to increase the temperature is utilised in changing the state by overcoming the forces of attraction between the particles. Therefore, this heat does not contribute in increasing the temperature of the substance.
Question 4: Suggest a method to liquefy atmospheric gases.
Answer: By applying pressure and reducing the temperature, atmospheric gases can be liquefied.
Page No: 10
Question 1: Why does a desert cooler cool better on a hot dry day?
Answer: When a liquid evaporates, the particles of the liquid absorb energy from the surroundings to compensate the loss of energy during evaporation. This makes the surroundings cool. In a desert cooler, the water inside it is made to evaporate. This leads to absorption of energy from the surroundings, thereby cooling the surroundings. Again, we know that evaporation depends on the amount of water vapour present in air (humidity). If the amount of water vapour present in air is less, then evaporation is more. On a hot dry day, the amount of water vapour present in air is less. Thus, water present inside the desert cooler evaporates more, thereby cooling the surroundings more. That is why a desert cooler cools better on a hot dry day.
Question 2: How does water kept in an earthen pot (matka) become cool during summers?
Answer: There are some pores in an earthen pot through which the liquid inside the pot evaporates. This evaporation makes the water inside the pot cool. In this way, water kept in an earthen pot becomes cool during summers.
Question 3: Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Answer: When we put some acetone or petrol or perfume on our palm, it evaporates. During evaporation, particles of the liquid absorb energy from the surrounding or the surface of the palm to compensate for the loss of energy, making the surroundings cool. Hence, our palm feels cold when we put some acetone or petrol or perfume on it.
Question 4: Why are we able to sip hot tea or milk faster from a saucer than a cup?
Answer: A liquid has a larger surface area in a saucer than in a cup. Thus, it evaporates faster and cools faster in a saucer than in a cup. For this reason, we are able to sip hot tea or milk faster from a saucer than a cup.
Question 5: What type of clothes should we wear in summers?
Answer: We should wear cotton clothes in summers. During summers, we sweat more. On the other hand, cotton is a good absorber of water. Thus, it absorbs sweat from our body and exposes the liquid to the atmosphere, making evaporation faster. During this evaporation, particles on the surface of the liquid gain energy from our body surface, making the body cool.
Why are Matter in Our Surroundings Class 9 Notes important?
Taking good notes for Matter in Our Surroundings Class 9 is important for the following reasons:
- Helps in better understanding of the topic
- Provides a quick reference for future revisions
- Helps in retaining the key concepts and ideas covered in the class
- Makes preparation for exams and tests easier
What are the key concepts covered in Matter in Our Surroundings Class 9?
Matter in Our Surroundings Class 9 covers a range of key concepts related to matter. Here are some of the key concepts that you can expect to learn from this topic:
- What is Matter?
- Characteristics of Particles of Matter
- States of Matter
- Change of State of Matter
- Evaporation
- Effect of Change of Pressure
- The Effect of Temperature on Matter
- The Concept of Latent Heat
How can you take effective Matter in Our Surroundings Class 9 Notes?
Here are some tips that can help you take effective Matter in Our Surroundings Class 9 Notes:
- Start by reviewing the topic before the class. This will help you to understand the key concepts that will be covered in the class.
- Use a notebook or a digital note-taking app to take your notes. Make sure that you have plenty of space to write down your notes.
- Write down the key concepts and ideas in your own words. This will help you to better understand the material.
- Use bullet points, diagrams, and illustrations to help you remember the material.
- Highlight or underline important concepts and ideas.
- Organize your notes by topic or subtopic. This will make it easier to review your notes later.
- After the class, review your notes and fill in any gaps. This will help you to reinforce your understanding of the material.
FAQs related to Matter in Our Surroundings Class 9 Notes
How can I study effectively for Matter in Our Surroundings Class 9?
To study effectively for Matter in Our Surroundings Class 9, make sure to review the key concepts before the class, take effective notes during the class, and revise the material regularly. You can also practice solving questions and take mock tests to evaluate your understanding of the topic.
What is the importance of understanding Matter in Our Surroundings in daily life?
Understanding Matter in Our Surroundings is important in daily life as it helps us to understand the properties of matter, its behavior under different conditions, and the changes that it can undergo. It also helps us to understand the processes such as evaporation, sublimation, and condensation, which are involved in our daily life activities such as cooking, drying, and refrigeration.
How can I make my Matter in Our Surroundings Class 9 Notes more effective?
To make your Matter in Our Surroundings Class 9 Notes more effective, you can use different colored pens or highlighters to differentiate between different concepts, use diagrams and flow charts to represent the information in a visual form, and practice writing short summaries or summaries for each concept to reinforce your understanding of the material.
Conclusion:
Matter in Our Surroundings is an important topic covered in Class 9 Science. By taking good Matter in Our Surroundings Class 9 Notes, you can better understand the material covered in the class, retain the key concepts and ideas, and prepare for exams and tests more effectively. So, make sure to use the tips provided in this blog post to take effective notes for Matter in Our Surroundings Class 9, and you will be well on your way to mastering the subject of Science.
Chapter 2 ………………..
SOLUTION of chapter 2