Aakash Repeater Courses
ApplyTake Aakash iACST and get instant scholarship on coaching programs.
Everything around us is made up of matter. This includes the air we breathe, the water we drink, and all of the products we use on a daily basis. Matter is anything that has weight and occupies space. This chapter, "Matter in Our Surroundings," will teach us about matter, its numerous forms, and how it evolves in different contexts. Understanding matter is very important because it is the base of everything we see and use in the world. This topic is detailed in the NCERT Notes for Class 9 and fits into the CBSE syllabus, which helps students understand Chemistry better.
The matter we see around us generally comes in three forms: solid, liquid, and gas. Take water as an example—it’s ice when it’s cold, water when it's warm, and steam when you heat it up. Matter can switch between these forms, which is important in nature and in everyday life. Think about melting ice caps because of climate change or how fridges and air conditioners work. In this chapter, students will learn about the different properties of matter, how it acts in different situations, and why all of this matters in real life.
Also, students can refer to
NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings |
NCERT Exemplar Class 9 Science Chapter 1 Matter in Our Surroundings |
Topics of Class 9 of Science Matter in our Surroundings
Matter in Our Surroundings |
Matter in Our Surroundings (Introduction) |
Physical Nature of Matter |
Characteristics of Particles of Matter |
States of Matter |
Can Matter Change its State? |
Evaporation |
Definition of Matter: Anything that occupies space and has mass is referred to as matter.
Let's discuss its classification on the basis of physical properties.
How small are these particles?
Particles of matter have spaces between them
Particles of matter are continuously moving
Particles of matter attract each other
It has been observed that force of attraction is present between particles of matter and the strength of this force of attraction depends upon the kind of matter.
Matter exists in three different states, viz Solid, liquid and gas.
These different states of matter exist due to variations in their characteristics and properties discussed above.
Following are the characteristic features of solids :
They possess a definite size (Volume) and a definite shape
The shape of solid can be changed but it usually requires considerable force
They are generally hard and rigid
They have negligible compressibility
Eg. Iron, silver, common salt etc.
Following are the characteristic features of Liquid :
They possess a definite volume but no definite shape
It takes up the shape of the container in which it is placed
They also have a tendency to flow.
They are fluid and have very high diffusion capacity
Particles move freely and are having greater spaces between them
For Eg. Water, alcohol, milk, oil etc.
Following are the characteristic features of Gases :
They neither possess a definite volume nor definite shape.
They are having very high compressibility
Particles of gases are having the highest diffusion rate.
Particles move randomly and very fast.
For Eg. air, Carbon dioxide, oxygen, hydrogen etc.
We can take the example of water, as we know that it exists in all 3 states i.e.
Solid as ice
Liquid as its familiar water state
Gas as vapour
Now we need to look into reasons those are responsible for bringing out these changes in the state of matter.
Following are the factors which affect evaporation (e.g., drying of wet clothes)
Surface Area: As we know, evaporation is a surface phenomenon and with an increase in temperature, the rate of evaporation also increases
Temperature: With the increase in temperature, the particles are able to get more heat energy and thereby more kinetic energy, and they are able to escape into the atmosphere more easily.
Decrease in Humidity: It helps in increasing evaporation, as when humidity is higher than the number of water particles in the surrounding area, fewer water particles will be able to get into the area.
Increase in Wind Speed: This helps in increasing the evaporation as those water vapours are able to move away from the cloth with the help of the wind. Also, the surrounding air has a smaller number of water particles so that more water vapours can evapourate there
Question 1:
In which of the following conditions, the disrtance between the molecules of hydrogen gas would increase?
(i) Increasing pressure on hydrogen contained in a closed container
(ii) Some hydrogen gas leaking out of the container
(iii) Increasing the volume of the container of hydrogen gas
(iv) Adding more hydrogen gas to the container without increasing the volume of the container
(a) (i) and (iii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer 1: C
Molecules of gas acquire the complete volume of container.
These molecules move randomly inside the container, therefore the average molecular separation can be calculated by assuming the given number of molecules in given volume.
It is easy to understand, that the average molecular separation will increase by either increasing the volume keeping number of molecules constant or by decreasing number of molecules keeping volume constant.
Increasing pressure will lead to increase in temperature of a gas in closed container. This will increase the kinetic energy of molecules. Therefore, it will not help in increasing distance between molecules.
Hence statement numbers (i) and (iii) are correct which will lead to correct answer as option C.
Question 2:
Which condition out of the following will increase the evaporation of water?
(a) Increase in temperature of water
(b) Decrease in temperature of water
(c) Less exposed surface area of water
(d) Adding common salt to water
Answer 2:A
In case of evaporation, some liquid molecules take energy from rest of the liquid molecules and get converted in vapour.
If we increase the temperature of any liquid, it would be easy for some molecules to take the energy from rest of the molecules. As at higher temperature, all of them have higher amount of energy which will help process of evaporation.
The process of evaporation will be supported by exposure of surface to the surrounding, hence higher surface area leads to higher evaporation.
When we add common salt in water, some part of this salt covers the surface area along with water molecules which will create obstacles in evaporation.
Hence the correct answer of this question is option A.
1. Revise all the Basics of Matter
Matter occupies space and has mass.
States of Matter are :
Solid that have a fixed shape and volume (e.g., Ice).
Liquid have a fixed volume but no fixed shape (e.g., Water).
Gas has no fixed shape or volume (e.g., Oxygen).
2. Focus on Basic Key Concepts
A. Physical Nature of Matter
Particle Theory:
Matter is made of tiny particles.
Particles have space between them (intermolecular space).
Particles are in constant motion (kinetic energy).
B. States of Matter & Their Properties
Property | Solid | Liquid | Gas |
Shape | Fixed | Take container shape | Fills entire container |
Volume | Fixed | Fixed | Variable |
Compressibility | Negligible | Low | High |
Density | High | Moderate | Low |
C. Changes of State
Melting: Solid → Liquid (Heat absorbed).
Freezing: Liquid → Solid (Heat released).
Evaporation: Liquid → Gas (at any temperature).
Boiling: Liquid → Gas (at boiling point).
Condensation: Gas → Liquid (Cooling).
Sublimation: Solid → Gas directly (e.g., Camphor, Dry Ice).
D. Factors Affecting Evaporation
With increase in temperature, rate of evaporation increases.
With increase in surface Area, rate of evaporation increases.
With dercrease in Humidity, rate of evaporation increases.
With increase in wind speed, rate of evaporation increases.
E. Latent Heat
Latent Heat of Vaporization is the heat required to boil 1 kg of liquid into gas.
4. Important Formulas & Units
Density = Mass / Volume (Unit: kg/m³ or g/cm³).
Kelvin to Celsius:
$\mathrm{K}={ }^{\circ} \mathrm{C}+273$
5. Practice Diagrams
Particle arrangement in solids, liquids, and gases.
Temperature vs. Time graph during state changes.
6. Common Mistakes to Avoid
Confusion in evaporation (surface phenomenon) and boiling (bulk phenomenon).
Always remember that intermolecular spaces are larger in gases than in solids.
Misusing the units (e.g., using °C instead of Kelvin in gas laws).
The Matter in Our Surroundings Class 9th notes will assist you in revising the chapter and gaining an understanding of the main concepts addressed. These Notes are also not complicated, and they thoroughly explain step-by-step approaches to guarantee that students understand the concepts of this chapter, which is part of the CBSE Science syllabus for class 9. The Matter in Our Surroundings class 9 notes pdf download can be utilised for offline preparation.
NCERT Class 9th Science Chapter 1 Notes |
Matter is anything that has mass and occupies space. In simpler terms, it's anything you can touch, see, or feel (and even some things you can't directly see, like air!). Everything around us, from a tiny grain of sand to a massive star, is made up of matter.
The temperature of a substance remains constant or the same during a transition of state because all of the heat or energy delivered to particles of matter is used to separate the particles of matter from each other.
No, energy is not matter. Energy is the ability to do work. While energy can affect matter (e.g., heat can change the state of matter), it doesn't have mass and doesn't occupy space in the same way as matter. Examples of energy include heat, light, sound, and electricity.
The three common states of matter are solid, liquid, and gas. There's also a fourth state called plasma, but it's less commonly encountered in everyday life.
Take Aakash iACST and get instant scholarship on coaching programs.
This ebook serves as a valuable study guide for NEET 2025 exam.
This e-book offers NEET PYQ and serves as an indispensable NEET study material.
As per latest syllabus. Physics formulas, equations, & laws of class 11 & 12th chapters
As per latest syllabus. Chemistry formulas, equations, & laws of class 11 & 12th chapters
As per latest 2024 syllabus. Study 40% syllabus and score upto 100% marks in JEE