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
1.5.1 Factors Affecting Evaporation
1.5.2 How Does Evaporation Cause Cooling?
NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings
Topic 1.2 Characteristics of particles of matter
Q 1. Which of the following is matter?
Chair, air, love, smell, hate, almonds, thought, cold, lemon water, the smell of perfume.
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.
CBSE NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings
Topic 1.3 State of Matter
Q 2.(a) Tabulate the differences in the characteristics of states of matter.
The difference in the characteristics of three states of matter-
- Solid has fixed form
- liquid has no fixed shape
- gas has no fixed shape
- Solid has fixed volume
- the fluid has fixed volume
- gas has no fixed volume
- 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
Q 2.(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
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.
NCERT textbook solutions for class 9 science chapter 1 Matter in Our Surroundings
Topic 1.4 Can matter change its state?
Q 1. Convert the following temperature to Celsius scale:
a. 300 K
b. 573 K.
It is known that,
TK = Temperature in Kelvin and
TC = temperature in Celsius.
(i) Temperature(C) = 300 - 273 = 27
(ii) Temperature (C) = 573 - 273 = 300
Q 2. What is the physical state of water at:
The primary state of water is liquid at room temperature. It changes to the gaseous state above . At water (liquid) can be in equilibrium with the gaseous state.
Hence, (i) At 250 physical state of water is gas. and,
(ii) At 100 physical state of water can be gas as well as liquid.
Q 4. Suggest a method to liquefy atmospheric gases.
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
Q 1. Why does a desert cooler cool better on a hot dry day?
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.
Q 2. How does the water kept in an earthen pot (matka) become cool during summer?
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.
Q 5. What type of clothes should we wear in summer?
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.
Q 3.(a) Give reason for the following observations.
Naphthalene balls disappear with time without leaving any solid because it can sublimise and directly converts into the gaseous state without leaving any solid.
Q 5. What is the physical state of water at-
(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 but at this temperature, it (liquid water) is in equilibrium with the gaseous state.
And Below 0 it changes into solid and also at this temperature it (liquid water) is in equilibrium with the solid state.
(i) At 25 water is in the liquid state
(ii) At 0 it can be liquid or solid and
(iii) At 100 it can be liquids or the gaseous state.
Q 6.(a) Give two reasons to justify-
Water at room temperature is a liquid because-
- Below 0 it converts to ice (solid)
- Above 100 it converts into the gaseous state.
Q 6.(b) Give two reasons to justify-
An iron almirah is a solid at room temperature because-
- At room temperature, it has definite shape and boundaries. Also, it has a fixed volume.
- The melting point of iron is much higher than room temperature.
Q 9. Name A,B,C,D,E and F in the following diagram showing change in its state
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.
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