# NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings

NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings: If you are looking for solutions for NCERT class 9 science chapter 1 Matter in Our Surroundings then you are at the right place. This article contains step by step solutions to each question. The detailed NCERT solutions to all the exercise questions provided here will help you to understand the fundamental concepts involved in chapter 1 Matter in our Surroundings. As we know the matter is made up of particles and as we look at our surroundings, we see a large variety of things with different shapes, sizes, and texture. Through CBSE NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings, you will be able to understand the questions and its concepts related to some important topics of this chapter.

Here are important topics of chapter 1 Matter in Our Surroundings:

1.1 Physical Nature of Matter

1.1.1 Matter Is Made up of Particles

1.1.2 How Small Are These Particles of Matter?

1.2 Characteristics of Particles of Matter

1.2.1 Particles of Matter Have Space Between Them

1.2.2 Particles of Matter Are Continuously Moving

1.2.3 Particles of Matter Attract Each Other

1.3 States of Matter

1.3.1 the Solid State

1.3.2 the Liquid State

1.3.3 the Gaseous State

1.4 Can Matter Change Its State?

1.4.1 Effect of Change of Temperature

1.4.2 Effect of Change of Pressure

1.5 Evaporation

1.5.1 Factors Affecting Evaporation

1.5.2 How Does Evaporation Cause Cooling?

## Topic 1.2 Characteristics of particles of matter

Anything which has mass and occupies space is called matter. It is made up of particles.

In the above question, chair, air, almonds, and lemon water are matters.

And love, smell, hate, thought, cold and smell of perfume are not in the category of matters because they are feeling and emotion of human beings and do not acquires any space.

The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close. The smell of hot sizzling food reaches you several meters away

The smell of hot sizzling food reaches us from several metres away, as the particles of hot have more kinetic energy than the cold food.

So, the rate of diffusion is more in hot food as compare to cold food.

A diver is able to cut through water in a swimming pool. It shows that the particles of matter (Water) have space between them and have less inter molecular forces of attraction.

There are three characteristics of the particles of matter -

1. The particle of matter has space between them.
2. Particles of matter are continuously moving.
3. The particle of matter attracts each other.

CBSE NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings

Topic 1.3 State of Matter

Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water, chalk, cotton, and iron.

Increasing order of the density-
Air < exhaust from chimneys < cotton < water < honey < chalk < iron

The difference in the characteristics of three states of matter-

(i) Shape-

• Solid has fixed form
• liquid has no fixed shape
• gas has no fixed shape

(ii) Volume-

• Solid has fixed volume
• the fluid has fixed volume
• gas has no fixed volume

(iii) Rigidity/fluidity-

• Solids are rigid and cannot flow
• fluid can flow and have no any rigidity
• gas can flow and have no rigidity

(iv) Intermolecular force and space-

• Solids have a high intermolecular force and less space
• liquid has an intermediate intermolecular force and has space more than solids
• Gas has a very less intermolecular force and has high space

Rigidity- The tendency of a substance to maintain their shape when subjected to an external force.

Compressibility- It means the contraction in the volume of a substance under the applied pressure. Liquid and gas are compressible because they have empty space, but solid does not.

Fluidity- The tendency of a particle to flow is known as fluidity. Liquids and gases can flow.

Filling of a gas container- The gases can fill the container with a large amount when we applied external pressure.

Shape- Solids have fixed shapes and boundaries. Liquid and gases have no fixed shape and definite boundaries.

Kinetic energy- The energy possessed by particles due to their motion is known as kinetic energy. Gas has maximum kinetic energy as they have more random motion.

Q 3.(a)   Give reasons

A gas fills completely the vessel in which it is kept.

The molecules of gas can have the tendency to move in all random direction due to their high kinetic energy.

Q 3. (b)  Give reasons

A gas exerts pressure on the walls of the container because the molecules of the gas are continuously in random motion because of their high kinetic energy.

So, that the molecules of gas vibrating and hitting on the walls of the container and as a result exerts pressure on walls.

Q 3.(c)   Give reasons

A wooden table should be called a solid because it has a definite shape, fixed volume and a definite boundaries. Also, it cannot flow and incompressible.

Q 3.(d)   Give reasons

We can easily move our hand in the air but to do the same through a solid block of wood we need a karate expert because, in air, there is a less force of attraction between the particles. So, very less amount of external force can break it.

But in the case of solid, the force of attraction is very strong and the molecular space is so high. Hence a large amount of force is required to break it.

Ice is solid but its density is lower than that of water due to its network structure and forms a cage-like structure with a lot of vacant space. So that's why ice floats on water.

## NCERT textbook solutions for class 9 science chapter 1 Matter in Our Surroundings

Topic 1.4 Can matter change its state?

a.  300 K

b.  573 K.

It is known that,
$T_K = 273 + T_c$
TK  = Temperature in Kelvin and

T = temperature in Celsius.

Therefore,

(i)  Temperature(C) = 300 - 273  = 27 $^0C$

(ii) Temperature (C) = 573 - 273 = 300 $^0C$

a.     250ºC
b.     100ºC

The primary state of water is liquid at room temperature. It changes to the gaseous state above $100^0C$. At $100^0C$ water (liquid) can be in equilibrium with the gaseous state.

Hence, (i) At 250 $^0C$ physical state of water is gas. and,

(ii) At 100 $^0C$ physical state of water can be gas as well as liquid.

The temperature of the substance does not change because the heat is used to overcome the forces of attraction.

This heat energy is known as latent heat.

That is why for any substance, the temperature remain constant during the change of state.

The atmospheric gases are transferred into a cylinder with a piston attached on it. By cooling and applying external pressure(by pushing the piston) on them. This way gases can be liquified.

## CBSE NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings

Topic 1.5 Evaporation

A desert cooler cools better on a hot and dry day. It is because the inner walls of the cooler get sprinkled by the water continuously and due to warm, dry weather, this water gets evaporated.

Evaporation cause cooling of the present air inside of the cooler. This cold air is sent in the room by a fan.

The water inside the earthen pot become cold during the summer because the earthen pot is porous with a lot of pores in it. So, water comes out on the surface of the earthen pot, and this water gets evaporated.

And thus the temperature of water present inside the pot has a much lower temperature than outside, and hence water becomes cold.

When we put some acetone, petrol or perfume evaporate in our palm, they come into contact with the air and hence evaporation causes a cooling effect on our palm.

As we know, the evaporation is rate is faster with the increased surface area. Tea in a saucer has a larger surface area than in a cup.

Therefore, the cooling of tea is more rapid in the saucer, and thus, we can sip hot tea or milk faster from a saucer rather than a cup.

We should wear light coloured cotton clothes because the light colours reflect the solar radiation and cotton cloths have more porosity so that it allows sweat through it to evaporate faster, thereby causing a cooling effect.

## NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings- Excercise solutions

(a)     293 K
(b)     470 K.

It is known that,
$T_K = 273 + T_c$
TK  = Temperature in Kelvin and

T = temperature in Celsius.

Therefore,

(i) Temperature ($^0C$)  = (293 - 273) = 20 $^0C$

(ii) Temperature ($^0C$)  = 470 -273 = 197$^0C$

(a)     25°C
(b)     373°C.

It is known that,
$T_K = 273 + T_c$
TK  = Temperature in Kelvin and

T = temperature in Celsius.

Therefore,

(i) Temperature (K) = 273 + 25 = 298 K

(ii) Temperature (K) = 273 + 373 = 646 K

Naphthalene balls disappear with time without leaving any solid because it can sublimise and directly converts into the gaseous state without leaving any solid.

Perfumes contain a volatile solvent which diffuses very faster and due to this, we can get the smell of perfume sitting several meters away.

the general increasing order of forces of attraction in three states of matter is gas < liquid < solid.

Therefore increasing order for the above-given substance is-

Oxygen < water < sugar

(a) 25°C      (b) 0°C     (c) 100°C ?

The primary physical state of water is liquid. It converts into gaseous state at a temperature above 100 $^0C$ but at this temperature, it (liquid water) is in equilibrium with the gaseous state.

And Below 0 $^0C$ it changes into solid and also at this temperature it (liquid water) is in equilibrium with the solid state.

Therefore;

(i) At 25 $^0C$ water is in the liquid state

(ii) At 0$^0C$ it can be liquid or solid and

(iii) At 100 $^0C$ it can be liquids or the gaseous state.

Q 6.(a)   Give two reasons to justify-

Water at room temperature is a liquid because-

1. Below 0 $^0C$ it converts to ice (solid)
2. Above 100 $^0C$ it converts into the gaseous state.

Q 6.(b)  Give two reasons to justify-

An iron almirah is a solid at room temperature because-

1. At room temperature, it has definite shape and boundaries. Also, it has a fixed volume.
2. The melting point of iron is much higher than room temperature.

At 273K ice can easily absorb more heat energy from the surrounding in the form of latent heat and overcome the fusion to become water.

Water does not absorb this extra heat from the medium.

Thus the cooling effect of ice is more than water at the same temperature.

Steam at 100 $^0C$ produces more severe burns.

It is because extra heat is hidden in it called latent heat, whereas the boiling water doesn't have any this hidden heat.

In the above flow chart-

A = fusion/ melting/ liquefication

B = Vaporisation/ evaporation

C = Condensation (transformation of water from a gaseous state to liquid state)

D = Solidification (the conversion of liquid into solid is known as solidification)

E = F = Sublimation

Direct conversion of solid into gas or gas into solid without attaining the liquid phase is called sublimation.

## NCERT Solutions for Class 9 Science- Chapter Wise

 Chapter No. Chapter Name Chapter 1 NCERT solutions for class 9 science chapter 1 Matter in our surroundings Chapter 2 CBSE NCERT solutions for class 9 science chapter 2 Is Matter Around Us Pure Chapter 3 Solutions for NCERT class 9 science chapter 3 Atoms and Molecules Chapter 4 NCERT textbook solutions for class 9 science chapter 4 Structure of The Atom Chapter 5 NCERT solutions for class 9 science chapter 5 The Fundamental Unit of Life Chapter 6 CBSE NCERT solutions for class 9 science chapter 6 Tissues Chapter 7 NCERT free solutions for class 9 science chapter 7 Diversity in Living Organisms Chapter 8 solutions for NCERT class 9 science chapter 8 Motion Chapter 9 NCERT textbook solutions for class 9 science chapter 9 Force and Laws of Motion Chapter 10 CBSE NCERT solutions for class 9 science chapter 10 Gravitation Chapter 11 NCERT solutions for class 9 science chapter 11 Work and Energy Chapter 12 Solutions for NCERT class 9 science chapter 12 Sound Chapter 13 CBSE NCERT solutions for class 9 science chapter 13 Why Do We Fall ill? Chapter 14 NCERT free solutions for class 9 chapter 14 Natural Resources Chapter 15 NCERT textbook solutions for class 9 science chapter 15 Improvement in Food Resources

## NCERT Solutions for Class 9 - Subject Wise

Key Features of NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings:

• All the NCERT solutions for the class 9 are created by experienced faculties.
• These solutions are easy to understand.
• Solutions of the questions given in class 9 chapter 1 Matter in Our Surroundings are as per the CBSE guidelines.
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