Here, you will learn about ‘Earth air water. This is for students of class five. In the end, there will be a test based on the texts mentioned below.
The chapter-‘Earth air water’ is very interesting. I hope, students of all classes will get help from this.
Formation of the earth
Earth is our residential planet. It is third planet in our solar system.
Earth is the 5th largest planet in the solar system.
The name of our home planet is 1000 years old. Approximately 4.5 billion years ago, earth had been formed when gravity started playing.
Gravity started pulling the gases, dusts towards earth’s surface to become the third planet in our solar system. Then the layout of the solar system settled.
Interior of the earth
The interior of the earth is divided into three parts. These are: crust, mantle and core.
Crust
- The outermost layer
- It is made of many rocks.
- And ranges from 5- 70 kilometres in depth.
- The rock of the crust is of the two types: sial and sima
- The age of solid crust is approximately 4.4 billions.
Mantle
- It extends to a depth of 2890 km.
- The planet’s thickest layer, it is.
- It is divided into two parts- upper mantle and lower mantle.
- These two zones are separated by a transition zone.
- It consists of silicate rocks which are richer in Iron and magnesium.
Core
- Within the Earth’s core, denser material exists.
- Core is divided into two parts-one solid inner core and the other liquid outer core.
- Inner core is composed of iron and nickel.
- The inner core of earth may rotate faster than the rest of the planet.
Movements of the earth
There are two types movements of the earth:
Rotation
- The earth spins on its axis. This movement is called rotation.
- It spins very fast and takes 24 hours to complete one rotation.
- Half of the earth receives light from the sun and thus there will have day at that time. Another half will have night.
- Day and night occurs due to the rotation of the earth.
Revolution
- The earth moves around the sun. This movement is called as revolution.
- It takes 365 days to complete one revolution.
- One solar year means 365 days.
More details in –
https://en.wikipedia.org/wiki/Earth
Air and its composition
- Air exists around us. We can feel it though we can’t see it.
- It is a mixture of gases.
- There are many gases in air which are essential for the plants and animals.
- There are oxygen, nitrogen, hydrogen, carbon dioxide, and some other gases.
Nitrogen
- Living animals don’t use nitrogen directly from the air.
- Animals get nitrogen from fish, meat and plants.
- Plants get nitrogen from the soil.
- Nitrogen does not support burning. It keeps the process of burning under control.
Oxygen
- All the animals require this gas for breathing.
- It helps in burning.
Carbon-Dioxide
- It is essential for green plants to carry out photosynthesis.
- It helps in keeping our atmosphere warm.
Other gases
- Gases like Helium, Neon, Argon, Methane, Hydrogen are also present in the air.
- To fill in balloons, we use Helium.
- To produce the colourful glow in bulbs and fluorescent tubes, we use Argon.
- We use Methane as a fuel.
- In light boards, television, and lasers with helium, we use Neon.
Humidity
- The amount of water vapour present in the air is called humidity.
- If there is more water vapours in it, air is called humid.
- Air is dry means humidity is low.
- We feel uncomfortable due to high humidity as our sweat does not evaporate easily.
Atmosphere and its layers
The blanket of air that surrounds the earth is called atmosphere. It consists of different types of layers. The temperature varies from layer to layer.
These layers are:
Troposphere
- This is the part of atmosphere where we live in.
- As the distance above the earth increases, temperature gets colder in this layer.
- 6.50C temperature rises per kilometre increment of height.
- 75% of all the air prevails in the atmosphere, is in the troposphere.
- Most of the weather i.e. rain, cloud, snow, etc. is in this layer.
- Tropopause is the top of the troposphere.
Stratosphere
- Approximately 50 km from the tropopause is known as stratosphere.
- Ozone dominates other gases in this layer.
- Ultaviolet radiation from the sun is absorbed by this ozone.
- Thus, ozone can’t enter the previous layer i.e. troposphere and protects us from diseases.
- As height increases, temperature increases in this layer.
Mesosphere
- The layer above the stratosphere is called mesosphere.
- In this layer, temperature decreases when height increases.
Thermosphere
- This layer of atmosphere starts just above the Mesosphere.
- It extends to 600 kilometers high from the top of the Mesosphere.
Exosphere
- Upper limit of our atmosphere.
- It extends upto 10,000 kilometers from the top of the thermosphere.
Ionosphere
- A layer of electrons, ionized atoms, and molecules that
- It overlaps into the mesosphere and thermosphere.
- Radio communication occurs due to this region.
Properties of air
Air
- is a mixture of gases
- has mass
- occupies space
- exerts pressure
- is needed for burning
- contains dust particles
- is effected by heat and altitude
- can be compressed
Water
All plants and animals need water for survival.
We can get the water by digging the ground and it falls from the sky when it rains.
Purification of water
There are many undesirable chemicals, suspended solids and gases in water which are not good for us. Hence, we need to purify the drinking water.
Water is purified to disinfect for our consumption.
Removal of soluble impurities
Soluble impurities are removed from water in following two ways-
Evaporation
You can make water vapour by applying heat on water but the impurities don’t. This process is called Evaporation. In this way, we can separate the impurities from water.
Distillation
First, we will make water vapour from water by boiling it. We will collect the water vapour. Then, we will make water again from this vapour by condensing it. This process is known as Distillation.
Removal of insoluble impurities
Insoluble impurities are removed through the following ways:
Sedimentation
Keep the water with insoluble impurities in a vessel for some time so that the impurities settle down at the bottom of the vessel. This is called sedimentation.
Decantation
After sometime, when all the impurities settle down, you pour the clean water stored at the top of the vessel into another vessel. This is called decantation.
Filtration
We can pass the water through a filter paper. Impurities can’t pass through it but water can. In this way, we can purify water. This is known as filtration.
MCQ based test on Earth air water
Students may consider this as a test of 25 marks. After completion of the test, they can check the answers by themselves and can come to know how much they are prepared.
The multiple-choice questions mentioned here are the basic questions from the chapter- “Earth air water” which will help the students of class five.
