# NCERT Solutions Class 9 Science Chapter 1: Matters in our Surrounding

Science is a fascinating subject, and it plays an essential role in students' lives. It provides numerous concepts which are discussed in higher classes. Anyone who wants to major in Science must undergo in-depth learning of these concepts

Class 9 Science Chapter 1: Matters in our Surrounding introduces many fundamental concepts about the matter, its composition, what are they made up of, etc. Although students may have learnt the concepts in their previous classes, this chapter brings new concepts such as diffusion, states of matter, and the physical nature of matter.

Students can visit the Extramarks website and access NCERT Solutions Class 9 Science Chapter 1 along with some other study resources. These resources allow students to get theoretical notes, illustrations, examples, past years’  papers, etc. With the help of these materials, students gain confidence and proficiency in Science.

Extramarks is among the most popular online learning platforms, which provides students with the most effective learning materials and solutions. It aims to help students develop the essential skills for better learning. NCERT Solutions for Class 9 Science Chapter 1 provides comprehensive explanations to the answers of the end-text NCERT questions which helps you build an understanding of all the concepts .

Students can also regularly visit the Extramarks website for the latest updates about the NCERT syllabus. In addition, students can also refer to other primary and secondary class solutions, including NCERT Solutions Class 10, NCERT Solutions Class 11, and NCERT Solutions Class 12.

## Key Topics Covered In NCERT Solutions Class 9 Science Chapter 1

NCERT Solutions Class 9 Science Chapter 1 introduces the fundamentals of matters and their characteristics. Here, students will learn about sublimation, evaporation, cooling effect, properties of matter, diffusion and the effect of the change in temperature and pressure.

Matter in Our Surrounding

Everything around us is matter. Such as a pencil, a pen, a table, food, and clothes. The matter is defined as the substances and materials that make up the cosmos. In other words, anything that occupies space has mass and can be sensed by our senses is considered matter.

Physical nature of mater

Physical properties are the observable or measured elements of matter without altering their form or composition. It's independent of the amount of matter in the environment. Physical characteristics include colour, appearance, smell, density, melting point, and boiling point.

Characteristics of particles of matter

Particles of matter have intermolecular spaces and are in continuous motion. It experiences forces from one another.

Following are the characteristics of particles of matter:

• Particles of matter have spaces between them:

This concept talks about the solubility of a substance in other substances. For example, there is no rise in the water level on dissolving sugar in water because sugar particles get into the interparticle.

• Particles of matter are constantly in motion:

It shows random movements due to the kinetic energy they possess. In addition, a rise in temperature increases the kinetic energy of the particles, making them move more vigorously.

• Particles of matter attract each other

Every substance has an interparticle force of attraction. We need to overcome this force to break a substance.

States of matter

The state of matter is classified into three forms: solids, liquids, and gases. The table below shows the difference between these three states of matter:

 Solids Liquids Gases Solids have strong intermolecular forces Liquids have weak intermolecular force Gases have feeble intermolecular forces It has less intermolecular space It has a sizeable intermolecular space It has a vast intermolecular space Solids have high-density melting and boiling point Liquids have low-density melting and boiling point Gases have a low melting point. It cannot be compressed It can be compressed It has very high compressibility Solids have fixed volumes and a definitive shape Liquids have fixed volumes but no fixed shape Gas particles are well separated with no regular arrangement. No definite shape and volume, takes the shape of the container

Diffusion is one of the features of matter and is determined by the movement of its particles. The phenomenon of diffusion occurs in solids, liquids and gases.

As the temperature of the dispersing medium increases, so does the rate of diffusion. Diffusion is slowest in solids, while it is faster in gases.

Can matter change its state

As temperatures rise, the kinetic energy of the particles grows, which causes them to move with more energy. Additionally, the force of attraction between particles decreases. They break free from their positions and start to move around freely. Furthermore, the condition of matter starts to change, and solids change their phase, resulting in liquids. Similar to liquids, liquids undergo a phase change to become gas.

• Melting point

It is defined as the temperature at which solids  convert into liquid at atmospheric pressure. The solid and liquid phases are in equilibrium during the high melting points.

• Boiling point:

It is defined as the temperature at which the vapour pressure of the liquid is equal to the atmospheric pressure. In simpler words, when liquid starts boiling & converting into gas at a certain temperature, that is known as its boiling point

• Sublimation

When a substance in a solid state changes into a gaseous state  without changing into the liquid state . This is called sublimation.

• Change in pressure:

When we apply pressure, the interparticle space between particles of matter decreases. Therefore, we can convert a solid into a liquid by applying pressure and reducing temperature.

One example is how the gas carbon dioxide gets converted into solid due to high pressure. On slowly decreasing the pressure the liquified gas will turn into gas. Solid carbon dioxide (also called dry ice) gets converted into gas without changing into liquid form on decreasing the pressure and increasing the temperature.

• Fusion:

Fusion takes place when a substance changes its form from a solid to a  liquid. Before melting, the strong intermolecular bonds hold the atoms, molecules or ions tightly together to retain the solid form. Upon heating the substance, the particles gain a good amount of kinetic energy and overcome the bonds that are holding them together. This results in the fusion of the heated substances.

• Latent Heat:

The heat energy that is required to change the state of a substance is called latent heat. It is known as latent heat as it gets absorbed into the substance that is changing state and doesn't get visible by increasing the temperature.

Students can refer to Extramarks NCERT Solutions Class 9 Science Chapter 1, where we have elaborated the key characteristic features of boiling and melting point.

Evaporation

Evaporation is the phenomenon of changing a liquid into its vapour state at any temperature below its boiling point. In other words, evaporation is a surface phenomenon.

Following are the factors affecting evaporation which are well elaborated in NCERT Solutions Class 9 Science Chapter 1:

An increase in surface area increases evaporation.

• Evaporation can cause a cooling effect.
• An increase in wind speed increases the rate of evaporation.
• A decrease in humidity increases the rate of evaporation.
• An increase in temperature may increase the rate of evaporation.

Some measurable quantities and their units:

 Quantity Unit Symbol Temperature Kelvin K Mass Kilogram kg Volume Cubic metre m3 Pressure Pascal Pa Length Metre m Weight Newton N Density Kilogram per cubic metre kg/m3

### NCERT Solutions Class 9 Science Chapter 1: Exercise &  Solutions

NCERT Solutions created by the subject experts at the Extramarks help students with their examination preparation. Students can start with a trial account by registering on the website. In addition, they can clear their doubts on topics in all the chapters. NCERT Solutions Class 9 Science Chapter 1 covers theoretical explanations and has step-by-step answers to the questions.

Chapter 1- Matters in our Surrounding has numerous questions, including multiple-choice questions, descriptive types, matching the following, and true or false questions. Students will witness additional questions at the end of the NCERT Solutions Class 9 Science Chapter 1. It helps to clear the concepts and improve their learning experience.

Students can click on the below links to view exercise specific questions and their solutions which are covered in the Extramarks NCERT Solutions Class 9 Science Chapter 1:

• Chapter 1: Exercise 1.1 Solutions: 4 Questions
• Chapter 1: Exercise 1.2 Solutions: 4 Questions
• Chapter 1: Exercise 1.3 Solutions: 4 Questions
• Chapter 1: Exercise 1.4 Solutions: 4 Questions
• Class 9 Science Chapter 1 Question Answer

Students can also explore NCERT Solutions for other classes on their website:

• NCERT Solutions Class 1
• NCERT Solutions Class 2
• NCERT Solutions Class 3
• NCERT Solutions Class 4
• NCERT Solutions Class 5
• NCERT Solutions Class 6
• NCERT Solutions Class 7
• NCERT Solutions Class 8
• NCERT Solutions Class 9
• NCERT Solutions Class 10
• NCERT Solutions Class 11
• NCERT Solutions Class 12

#### NCERT Exemplar for Class 9 Science

Science is an exciting subject, and it requires a deep understanding of the basic concepts. To better understand these concepts, the ability to solve diverse questions is always helpful. It helps to clear the confusion and to gain an understanding of concepts.

The NCERT Exemplar helps  students in developing their understanding of the subject. They have a variety of questions, each with different levels of difficulty. Questions are multiple-choice. Fill in the blanks, and match the following. It also includes objective questions, very short-answer types, short answer types, and lengthy answer type questions in Class 9 Chapter 1.

Students will be able to explore various sub-topics, such as the characteristics of matter, their role in our surroundings and the effect of temperature change. Additionally, they will recognize the crucial difference between latent heat of fusion and heat of evaporation.

#### Key Features of NCERT Solutions Class 9 Science Chapter 1

Extramarks has a specialised team of subject specialists who provide appropriate solutions to every topic covered throughout the chapter. Students who have difficulty answering the questions in the textbook can refer to the answer to gain a complete understanding of the topic.

The most notable characteristics of these study materials are:

• The solutions help resolve students' questions that may arise when studying the Chapter.
• Solutions from NCERT Solutions Class 9 Science Chapter 1 strictly follow the CBSE outline and the guidelines.
• Our NCERT Solutions contain the answer to all the questions from Chapter 1 of the Class 9 Science.
• It is prepared with the help of expert faculty  who have a thorough conceptual understanding and years of experience.
• Students can refer to NCERT Solutions Class 9 Science Chapter 1 to learn and understand the characteristics of matter.

Q.1 Convert the following temperatures to the Celsius scale.
(a) 293 K (b) 470 K

Ans-

$\begin{array}{l}\left(\text{a}\right)\text{Temperature in Celsius scale}=\text{Temperature in Kelvin scale}-\text{273}\\ \text{}=\text{293}-\text{2}73\\ \text{}=\text{20}{\text{\hspace{0.17em}}}^{\text{ο}}\text{C}\text{\hspace{0.17em}}\\ \left(\text{b}\right)\text{Temperature in Celsius scale}=\text{Temperature in Kelvin scale}-\text{273}\\ \text{}=\text{470}-\text{2}73\\ \text{}={\text{197}}^{\text{ο}}\text{C}\text{\hspace{0.17em}}\end{array}$

Q.2 Convert the following temperatures to the Kelvin scale.

(a) 25°C (b) 373°C

Ans-

$\begin{array}{l}\left(\text{a}\right)\text{Temperature in Kelvin scale = Temperature in Celsius scale+273}\\ \text{= 25+273}\\ \text{= 298K}\text{\hspace{0.17em}}\\ \left(\text{b}\right)\text{Temperature in Kelvin scale = Temperature in Celsius scale + 273}\\ \text{= 373+273}\\ \text{= 646K}\end{array}$

Q.3 Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.

Ans-

(a) Naphthalene is a sublimating substance. Therefore, naphthalene balls sublimate that is turns into vapour without changing into liquid. Therefore, they disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away because of diffusion. The molecules of perfume spread out through the air and reach to great distance.

Q.4 Arrange the following substances in increasing order of forces of attraction between the particles— water, sugar, oxygen.

Ans-

Oxygen is a gas; therefore, the force of attraction is negligible between its particles. Water is a liquid, so the force of attraction between its particles is more than liquid and less than solid. Since sugar is a solid, thus force of attraction between particles is greatest. Hence, the correct increasing order of forces of attraction between the particles is as follows

Oxygen < Water < Sugar

Q.5 What is the physical state of water at—
(a) 25°C (b) 0°C (c) 100°C ?

Ans-

(a) At 25°C water exists as a liquid, with some water vapour above the water surface
(b) At 0°C water can exist as a solid as well as a liquid. Small amount of water vapour will be present in the air above the water/ice mixture.
(c) At 100°C water can exist in both liquid and gaseous states.

Q.6 Give two reasons to justify—
(a) Water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.

Ans-

(a) Water has no fixed shape but has a fixed volume that is,it occupies the shape of the container in which it is kept. Boiling point of water is 100°C and its freezing point is 0°C but the room temperature is between 0 and 100 0°C, therefore, it is a liquid at room temperature.
(b) All the atoms in iron are very tightly packed at the room temperature. Also its melting and boiling point is very high as it is a metal. So it is a solid at room temperature.

Q.7 Why is ice at 273 K more effective in cooling than water at the same temperature?

Ans-

Ice is solid form of water which at its freezing point (273K) absorbs heat to get converted into liquid form at this constant temperature which is called the latent heat of fusion. When completely converted into water (liquid), it will absorb heat till its temperature becomes equal to that of the surrounding or the body to which it has contact.

But water at 273K will only absorb heat till its temperature becomes equal to that of the surrounding or the body to which it has contact.

Therefore, ice at 273 K more effective in cooling than water at the same temperature.

Q.8 What produces more severe burns, boiling water or steam?

Ans-

Steam contains more heat, in the form of latent heat, as compared to boiling water. So when steam comes in contact with skin it will give more heat than boiling water, so steam causes more severe burns.

Burns caused by steam are more severe than those caused by the boiling water; though both are at the same temperature (100 °C).This is because, steam has 540 kcal/kg (latent heat) more energy than boiling water. When steam condenses on skin, it gives out 540 kcal/kg more energy than the boiling water.

Q.9 Name A, B, C, D, E and F in the following diagram showing change in its state

Ans-

A. Fusion or melting
B. Vaporisation
C. Condensation
D. Solidification
E. Sublimation
F. Deposition

1. What subtopics are included in Chapter 1 in the NCERT Solutions for Class 9?

Students will study the following subtopics within NCERT Solutions Class 9 Science Chapter 1.

• Introduction related to the Chapter.
• Composition of matter.
• Properties of matter.
• Diffusion.
• States of matter.
• Sublimation and Evaporation.
• Latent heat of vaporisation and fusion.

2. What are the types of questions in Science Class 9 Chapter 1?

Students will witness multiple-choice questions, match the following, true or false and descriptive types of questions. Students will be able to answer various types of problems in Class 9 Science Chapter 1, which will help them increase their knowledge of critical topics.

3. What are the benefits of studying from NCERT Solutions Class 9 Science Chapter 1?

Sometimes, it’s difficult for students to comprehend the concepts and definitions in the chapter. So, Extramarks NCERT Solutions provide answers to all questions in the exercises. They explain every step to help students comprehend the detailed answers with ease.