GSEB Class 8 Social Science Solutions Chapter 2 What is Around Us

Answer The Following Questions:

 

Question 1. What do you know about our Earth ? Write a short note.
Answer: Our Earth is a part of the solar system. Among all the solar system members, only Earth has the right temperature, air, and water needed to support life. Earth was originally a giant ball of fire, which eventually cooled down over time. Various parts of Earth changed into solids, liquids, gases, or different life forms during this cooling process. These elements then created the four main spheres of Earth, which are:
1. Lithosphere,
2. Hydrosphere,
3. Atmosphere and
4. Biosphere.
In simple words: Our Earth is special because it has the right temperature, air, and water for living things. It started as a hot ball, cooled down, and formed four main parts: land, water, air, and life zones.

Exam Tip: When writing about Earth, remember to include its unique position in the solar system, its formation, and the four essential spheres that make life possible.

 

Question 2. How much time was taken by the Earth to reach its present form after being detached from the Sun? Why?
Answer: People believe that Earth was once a part of the Sun. It separated from the Sun due to a collision. After that, Earth was a huge ball of fire that cooled down over time. It took many millions of years to cool. Even though modern science has advanced significantly, it is still not fully confirmed how much time Earth required to reach its current state.
In simple words: Earth separated from the Sun and took millions of years to cool and form. We don't know the exact time, even with all our science.

Exam Tip: Highlight that Earth's formation was a long process involving cooling from a fiery state, and note that the exact timeline is still not precisely determined by science.

 

Question 3. How are the spheres of Earth interrelated?
Answer: All four spheres of Earth-lithosphere, hydrosphere, atmosphere, and biosphere-are connected very closely. Because of their combined influence, conditions favorable for life have appeared on Earth.
Lithosphere is helpful in many ways. It provides a home for people. It gives space for building houses, obtaining fresh water and land for growing crops, and also forests and useful minerals for various industries. Hydrosphere offers fresh water to all living organisms. Atmosphere provides essential oxygen to all living organisms. No life form can live without air and water.
The part of the lithosphere, hydrosphere, and atmosphere where living things exist is named 'Biosphere'. This is one of the most important spheres on Earth, as our planet is the only one in the solar system that possesses a biosphere. So, all four spheres are connected.
In simple words: Earth's four spheres (land, water, air, life) are tightly linked. Together, they create perfect conditions for life. Each sphere provides something vital, like homes, water, or oxygen, and the biosphere is the special zone where all life thrives because of this connection.

Exam Tip: Emphasize the interconnectedness of all four spheres and how each one contributes vital resources, making Earth uniquely suitable for life.

Fill In The Blanks With Appropriate Words:

 

Question 1. There are totally ............ spheres on the Earth.
Answer: There are totally four spheres on the Earth.
In simple words: Earth has four main parts, or spheres.

Exam Tip: Remember the four main spheres of Earth: lithosphere, hydrosphere, atmosphere, and biosphere.

 

Question 2. Lithosphere covers approximately ............ per cent of the surface of the Earth.
Answer: Lithosphere covers approximately \( 29 \% \) of the surface of the Earth.
In simple words: The land part of Earth covers about \( 29 \% \) of its surface.

Exam Tip: Recall that the lithosphere (land) covers less than one-third of Earth's total surface.

 

Question 3. The most prominent liquid component in the atmosphere is ............ .
Answer: The most prominent liquid component in the atmosphere is water.
In simple words: Water is the most important liquid found in Earth's air.

Exam Tip: Think about how clouds and rain form; this directly relates to water in the atmosphere.

 

Question 4. Hydrosphere which is made of water, makes ............ per cent of the surface of Earth.
Answer: Hydrosphere which is made of water, makes \( 71 \% \) per cent of the surface of Earth.
In simple words: The water part of Earth covers about \( 71 \% \) of its surface.

Exam Tip: Remember that water covers the majority of Earth's surface, more than two-thirds.

 

Question 5. ............ gas absorbs the ultra-violet rays of the sun.
Answer: Ozone gas absorbs the ultra-violet rays of the sun.
In simple words: Ozone gas stops harmful UV rays from the sun.

Exam Tip: The ozone layer is crucial for protecting life on Earth from harmful radiation.

Give The Meaning Of The Following Terms:

 

Question. (1) Lithosphere
Answer: The solid part of Earth where we live is known as the lithosphere. 'Litho' means 'Rock', and 'Sphere' means 'layer'. This layer covers about \( 29 \% \) of the Earth's surface and is roughly \( 64 \text{ km} \) to \( 100 \text{ km} \) thick. Landforms such as mountains, plateaus, plains, and valleys are visible on the lithosphere.
In simple words: The lithosphere is the hard, rocky outer layer of Earth, including continents and ocean floors.

Exam Tip: Define 'lithosphere' by its composition (rock) and its role as the landmass where geographical features are found.

 

Question. (2) Hydrosphere
Answer: The liquid part of Earth is called the 'Hydrosphere'. It includes oceans, seas, bays, straits, lakes, ponds, rivers, and other water bodies. The hydrosphere covers about \( 71 \% \) of the Earth's surface.
In simple words: The hydrosphere is all the water on Earth, like oceans, rivers, and lakes.

Exam Tip: Remember that the hydrosphere encompasses all forms of water on Earth's surface, making up the vast majority of our planet.

 

Question. (3) Atmosphere
Answer: The sphere of air that wraps around the Earth from all sides is named the 'Atmosphere'. It stretches up to about \( 1600 \text{ km} \) from Earth's surface and cannot be easily seen with the naked eye. Various gases, water vapor, dust particles, smoke, salt particles, micro-organisms, and other components make up the atmosphere, which is colorless, odorless, and transparent.
In simple words: The atmosphere is the blanket of air surrounding Earth, made of many gases and particles, and it's invisible.

Exam Tip: When defining the atmosphere, include its composition, transparency, and the fact that it envelops the Earth.

 

Question. (4) Biosphere
Answer: The part of the lithosphere, hydrosphere, and atmosphere where the living world exists is called 'Biosphere'. This is one of the important spheres on Earth, as it is the only planet in the solar system that has a biosphere. The biosphere includes humans, animals, plants, and tiny insects.
In simple words: The biosphere is the part of Earth where life exists, including land, water, and air where living things can be found.

Exam Tip: The biosphere is where life interacts with all other spheres, making it a critical zone for all living organisms.

 

Question. (5) Pollution
Answer: Pollution is the process where land, water, air, and other necessary components for life become degraded. This degradation is often referred to as 'Pollution'.
In simple words: Pollution happens when important things for life, like land, water, and air, get dirty or damaged.

Exam Tip: Define pollution as the contamination or degradation of essential natural resources, impacting life.

State Whether The Following Statements Are True Or False:

 

Question 1. The Earth is a member of the solar family.
Answer: True
In simple words: Earth is one of the planets that belongs to our solar system.

Exam Tip: Remember that Earth is the third planet from the Sun in our solar system.

 

Question 2. The proportion of water on the surface of Earth is less than the proportion of land.
Answer: False
In simple words: More of Earth's surface is covered by water than by land.

Exam Tip: Recall that water covers about \( 71 \% \) of Earth's surface, while land covers only about \( 29 \% \).

 

Question 3. The fresh water is a gift of hydrosphere.
Answer: True
In simple words: The hydrosphere gives us fresh water.

Exam Tip: Understand that the hydrosphere includes all water on Earth, which is the source of fresh water.

 

Question 4. Oxygen reduces the intensity of nitrogen.
Answer: False
In simple words: Oxygen does not make nitrogen less strong; they are different gases.

Exam Tip: Recall that nitrogen, in fact, helps to dilute oxygen in the atmosphere, preventing rapid combustion. They don't reduce each other's intensity in that manner.

Explain How The Following Are Related To Your Life:

 

Question. 1. Mountains
Answer: Mountains stop winds that carry moisture, causing rainfall on one side while the other side gets less rain. Mountains are home to lovely hill stations that attract tourists. Rivers beginning in mountains create fertile plains and provide us with fresh water.
In simple words: Mountains bring us rain, offer places for holidays, and are the source of rivers that make land good for farming and give us drinking water.

Exam Tip: When explaining the relationship, mention how mountains influence weather patterns (rain), provide recreational areas, and are sources of vital water resources (rivers).

 

Question. 2. Fields:
Answer: Different crops like grains, cash crops, and oil seeds are grown in various types of fields. Fertile fields give people food, which is very important for life.
In simple words: Fields grow all sorts of crops that give us the food we need to live.

Exam Tip: Focus on how fields are essential for agriculture, providing food and vital resources for human survival.

 

Question. 3. Rivers:
Answer: Rivers are like our mothers because they provide water for drinking and for watering crops. Fresh water from rivers is useful in many different ways.
In simple words: Rivers give us water to drink and to grow our food, helping us in many ways.

Exam Tip: Highlight the fundamental role of rivers as sources of drinking water and irrigation, supporting human life and agriculture.

 

Question. 4. Lakes:
Answer: Lakes and ponds supply water for drinking and also for irrigation. Bigger reservoirs are also helpful as ways for transport.
In simple words: Lakes give us drinking water and water for farms, and large ones can be used for travel.

Exam Tip: Mention both the utilitarian uses (drinking, irrigation) and the transportation aspect of larger lakes and reservoirs.

 

Question. 5. Forests:
Answer:
1. Forests stop the climate from becoming dry and harsh. They keep the weather cool and assist in bringing rains.
2. Forests block winds, which helps protect crops and stops deserts from spreading.
3. Wood obtained from forests is used for building houses, making furniture, and for fuel.
4. Forests offer raw materials for many industries.
In simple words: Forests help keep the climate cool and rainy, protect crops from wind, provide wood for homes and fuel, and supply materials for factories.

Exam Tip: Explain the multi-faceted benefits of forests, including their role in climate regulation, ecological protection, and provision of essential resources for human use.

Activities

 

Question. (1) Draw the picture of the spheres of the Earth given on page no. 6 of your textbook.
Answer: This is an activity requiring a drawing, so no written answer is provided.
In simple words: This activity asks you to draw the Earth's spheres from your book.

Exam Tip: Ensure your drawing clearly labels and depicts the lithosphere, hydrosphere, atmosphere, and biosphere as distinct layers or regions.

 

Question. (2) Locate using various colours oceans, seas, bays, lakes, straits, gulfs, etc. on the out-lined map of the world.
Answer: This is an activity requiring a map-based task, so no written answer is provided.
In simple words: This activity asks you to find and mark different water bodies on a world map using colors.

Exam Tip: Use a variety of colors and clear labels to differentiate between oceans, seas, lakes, and other water features on your map.

 

Question. (3) Make a list of natural events and human activities that have adversely affected various spheres of the Earth.
Answer: This is an activity requiring a list, so no written answer is provided.
In simple words: This activity asks you to list natural events and human actions that have harmed Earth's different parts.

Exam Tip: For natural events, consider earthquakes, volcanic eruptions, and tsunamis. For human activities, think about deforestation, pollution, and industrialization.

 

Question. (4) Find out the resources of pollution in you surrounding and study their effects as well as suggest solutions to eradicate it.
Answer: This is an activity requiring observation and analysis, so no written answer is provided.
In simple words: This activity asks you to identify pollution sources near you, understand their impact, and suggest ways to stop them.

Exam Tip: When suggesting solutions, focus on practical, actionable steps like reducing waste, using public transport, and promoting renewable energy sources.

Gseb Class 8 Social Science What Is Around Us? Intext Questions And Answers

 

Question 1. What would happen if there were no seas?
Answer: Fresh water is essential for living organisms. Rain is the primary source of fresh water, and rainwater comes only from oceans. If oceans did not exist, there would be no rain. Without rain, we would not get fresh water to drink. Without water, life on Earth cannot survive. So, we cannot imagine life without oceans.
In simple words: If there were no seas, there would be no rain, no fresh water to drink, and no life on Earth because oceans are crucial for the water cycle.

Exam Tip: Emphasize the vital role of oceans in the water cycle and their direct impact on the availability of fresh water for all life forms.

 

Question 2. On the basis of which experiences can you state that Atmosphere exists on the surface of Barth?
Answer: Based on the following experiences, we can say that the Atmosphere exists on Earth's surface:
1. We can feel air moving due to wind. We shiver because of cold winds in winter. The hot air in summer can burn our skin.
2. The growth of various life forms, like plants and animals, shows that air and moisture are present.
3. The presence of dust and smoke, which can be seen floating in the air, helps spread sunlight and causes various diseases respectively.
In simple words: We know the atmosphere is there because we feel wind, get cold or hot air, see plants and animals grow (they need air), and notice dust and smoke floating around.

Exam Tip: Provide clear, relatable examples from daily life to demonstrate the presence and effects of the atmosphere.

 

Question 3. If any element in the living world is destroyed, then what will be its effect on our lives? For instance, what would happen if birds were wiped out from the face of Earth?
Answer: Birds consume insects that harm crops. If birds were to disappear, then insects would destroy all the crops.
In simple words: If any living part of nature is removed, it affects us. For example, if birds vanished, insects would eat all our crops.

Exam Tip: Explain the concept of ecological balance by providing a specific example of how the removal of one species (birds) can have a cascading negative effect on others (crops due to insects).

Gseb Class 8 Social Science What Is Around Us? Additional Important Questions And Answers

 

Question 1. How many spheres does Earth have ?
(a) Two
(b) Four
(c) Three
(d) Five
Answer: (b) Four
In simple words: Earth is made up of four main parts or spheres.

Exam Tip: Always remember the four primary spheres of Earth: lithosphere, hydrosphere, atmosphere, and biosphere.

 

Question 2. How much surface area does the lithosphere occupy ?
(a) \( 98 \% \)
(b) \( 97 \% \)
(c) \( 71 \% \)
(d) \( 29 \% \)
Answer: (d) \( 29 \% \)
In simple words: The solid land part of Earth takes up about \( 29 \% \) of its total surface.

Exam Tip: Be precise with percentages: the lithosphere covers just under one-third of the Earth's surface.

 

Question 3. Which sphere of Earth cannot be seen ?
(a) Lithosphere
(b) Biosphere
(c) Atmosphere
(d) Hydrosphere
Answer: (c) Atmosphere
In simple words: The air surrounding Earth, called the atmosphere, is invisible.

Exam Tip: Think about the properties of air - it is colorless and transparent, making it unseen.

 

Question 4. Which sphere of Earth has neither colour nor taste or smell ?
(a) Hydrosphere
(b) Atmosphere
(c) Biosphere
(d) Lithosphere
Answer: (b) Atmosphere
In simple words: The air around Earth has no color, taste, or smell.

Exam Tip: This question tests your understanding of the physical properties of the atmosphere.

 

Question 5. Which is the main source of fresh water ?
(a) Rivers
(b) Lakes
(c) Wells
(d) Rain
Answer: (d) Rain
In simple words: Rain is the primary way we get fresh water.

Exam Tip: Understand that while rivers, lakes, and wells contain fresh water, rain is the initial and ultimate source for replenishing these bodies.

 

Question 6. How much surface area does hydrosphere cover ?
(a) \( 71 \% \)
(b) \( 97 \% \)
(c) \( 68 \% \)
(d) \( 78 \% \)
Answer: (a) \( 71 \% \)
In simple words: Water covers about \( 71 \% \) of Earth's surface.

Exam Tip: Remember the large proportion of Earth's surface covered by water compared to land.

 

Question 7. How deep are ocean trenches ?
(a) \( 8 \) to \( 9 \text{ km} \)
(b) \( 10 \) to \( 11 \text{ km} \)
(c) \( 5 \) to \( 6 \text{ km} \)
(d) \( 14 \) to \( 15 \text{ km} \)
Answer: (b) \( 10 \) to \( 11 \text{ km} \)
In simple words: Ocean trenches can be very deep, reaching about \( 10 \) to \( 11 \text{ km} \).

Exam Tip: The Challenger Deep in the Mariana Trench is the deepest known point, approximately \( 11 \text{ km} \) deep.

 

Question 8. How much of Earth's total water is in the oceans ?
(a) \( 71 \% \)
(b) \( 78 \% \)
(c) \( 80 \% \)
(d) \( 97 \% \)
Answer: (d) \( 97 \% \)
In simple words: Most of Earth's water, about \( 97 \% \), is found in the oceans.

Exam Tip: Understand that while Earth has abundant water, the vast majority is saline ocean water, with only a small fraction being fresh water.

 

Question 9. Up to how many kilometres above the surface does atmosphere extend?
(a) \( 1600 \)
(b) \( 1000 \)
(c) \( 1200 \)
(d) \( 1400 \)
Answer: (a) \( 1600 \)
In simple words: Earth's atmosphere reaches up to about \( 1600 \text{ km} \) from the surface.

Exam Tip: While the atmosphere technically extends very far, the density decreases significantly with altitude, with most weather occurring in the lower layers.

 

Question 10. What is the proportion of nitrogen in atmosphere?
(a) \( 71 \% \)
(b) \( 48 \% \)
(c) \( 78 \% \)
(d) \( 21 \% \)
Answer: (c) \( 78 \% \)
In simple words: Nitrogen makes up about \( 78 \% \) of the air around Earth.

Exam Tip: Remember that nitrogen is the most abundant gas in Earth's atmosphere.

 

Question 11. What is the proportion of oxygen in atmosphere ?
(a) \( 21 \% \)
(b) \( 48 \% \)
(c) \( 78 \% \)
(d) \( 25 \% \)
Answer: (a) \( 21 \% \)
In simple words: Oxygen makes up about \( 21 \% \) of the air around Earth.

Exam Tip: Be aware of the major atmospheric gases and their approximate percentages, especially nitrogen (78%) and oxygen (21%).

 

Question 12. Which atmospheric gas prevents ultra-violet rays of the Sun from reaching Earth ?
(a) Nitrogen
(b) Oxygen
(c) Ozone
(d) Hydrogen
Answer: (c) Ozone
In simple words: Ozone gas in the atmosphere protects us from the Sun's harmful ultra-violet rays.

Exam Tip: The ozone layer is crucial for blocking harmful UV radiation, which is essential for life on Earth.

 

Question 13. Which atmospheric gas reduces the intensity of oxygen?
(a) Ozone
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
Answer: (c) Nitrogen
In simple words: Nitrogen gas helps to make the effect of oxygen less strong in the atmosphere.

Exam Tip: Nitrogen acts as a diluent for oxygen, regulating combustion and preventing extremely rapid oxidative processes on Earth.

 

Question 14. Which component of atmosphere spreads sunrays in all directions?
(a) Oxygen
(b) Ozone
(c) Carbon dioxide
(d) Dust particles
Answer: (d) Dust particles
In simple words: Tiny dust bits in the air help spread sunlight everywhere.

Exam Tip: Remember that dust particles contribute to the scattering of sunlight, which is why the sky appears blue and sunlight reaches shaded areas.

 

Question 15. Which gas increases in volume in areas of heavy vehicular traffic ?
(a) Carbon monoxide
(b) Nitrogen
(c) Hydrogen
(d) Argon
Answer: (a) Carbon monoxide
In simple words: In busy traffic areas, the amount of carbon monoxide gas goes up.

Exam Tip: Carbon monoxide is a harmful pollutant released by vehicle exhaust, especially in high traffic zones.

 

Question 16. Which gas causes global' warming when increased in volume ?
(a) \( \text{O}_2 \)
(b) \( \text{H}_2 \)
(c) \( \text{N}_2 \)
(d) \( \text{CO}_2 \)
Answer: (d) \( \text{CO}_2 \)
In simple words: When there's more \( \text{CO}_2 \) gas, it causes the Earth to get hotter, which is called global warming.

Exam Tip: \( \text{CO}_2 \) (carbon dioxide) is a major greenhouse gas, meaning it traps heat in the atmosphere and contributes to climate change.

Fill In The Blanks With Proper Words Or Numbers:

 

Question 1. In the solar system, only ............ has favourable temperature, water and air to sustain life.
Answer: In the solar system, only Earth has favourable temperature, water and air to sustain life.
In simple words: Only our Earth in the solar system has the right temperature, water, and air for life to exist.

Exam Tip: Emphasize Earth's unique combination of conditions that make it habitable compared to other planets.

 

Question 2. The Earth was a huge ball of ............ at the time of its origin.
Answer: The Earth was a huge ball of fire at the time of its origin.
In simple words: When it first formed, Earth was a giant fiery ball.

Exam Tip: Recall that Earth began as a molten, intensely hot body before gradually cooling down.

 

Question 3. The lithosphere is composed of ............ and ............ .
Answer: The lithosphere is composed of rocks and soil.
In simple words: The land part of Earth is made up of rocks and soil.

Exam Tip: Understand that the lithosphere primarily consists of solid materials like rocks and loose surface material (soil).

 

Question 4. ............ and ............ gases of the atmosphere sustain life on Earth.
Answer: Oxygen and nitrogen gases of the atmosphere sustain life on Earth.
In simple words: Oxygen and nitrogen in the air help life continue on Earth.

Exam Tip: Oxygen is vital for respiration, and nitrogen is essential for plant growth and diluting oxygen.

 

Question 5. ............ gas in the atmosphere reduces the intensity of oxygen.
Answer: Nitrogen gas in the atmosphere reduces the intensity of oxygen.
In simple words: Nitrogen gas makes oxygen less concentrated in the air.

Exam Tip: Nitrogen acts as a diluent, preventing rapid reactions that would occur if oxygen were present in higher concentrations.

State Whether The Following Statements Are True Or False:

 

Question 1. As we go higher from the surface of Earth the volume of most gases reduces.
Answer: True
In simple words: As you go higher above Earth, there is less air and fewer gases.

Exam Tip: Atmospheric pressure and gas density decrease significantly with increasing altitude.

 

Question 2. Carbon dioxide is found more in the lower layer of air.
Answer: True
In simple words: More \( \text{CO}_2 \) is found closer to Earth's surface.

Exam Tip: Carbon dioxide is a heavier gas and tends to concentrate in the lower atmospheric layers, where most human and biological activity occurs.

 

Question 3. Sound can be heard only due to atmosphere.
Answer: True
In simple words: Sound needs air (atmosphere) to travel so we can hear it.

Exam Tip: Sound waves are mechanical waves that require a medium (like air, water, or solids) to propagate; they cannot travel in a vacuum.

 

Question 4. Only Earth, a planet of the solar system, has biosphere.
Answer: True
In simple words: Earth is the only planet in our solar system known to have a place where life exists (a biosphere).

Exam Tip: This highlights Earth's unique suitability for life, supported by its specific conditions and the interaction of its spheres.

 

Question 5. The amount of \( \text{CO}_2 \) decreases due to cutting of trees.
Answer: False
In simple words: Cutting down trees actually makes the amount of \( \text{CO}_2 \) go up, not down.

Exam Tip: Trees absorb \( \text{CO}_2 \) through photosynthesis, so deforestation leads to an *increase* in atmospheric \( \text{CO}_2 \), contributing to global warming.

Match The Pairs Correctly:

 

Answer:
(1) Lithosphere - (4) Residence of all living organisms including humans
(2) Atmosphere - (1) Sphere of various gases
(3) Biosphere - (2) Base of life sustainability
In simple words: Match each of Earth's spheres (Lithosphere, Atmosphere, Biosphere) with the description that best fits it from the given options.

Exam Tip: Carefully read each item in both sections and identify the best logical connection between them based on your understanding of Earth's spheres.

Answer The Following Questions In One Or Two Sentences:

 

Question 1. What is the characteristic of the Earth as a member of the solar system?
Answer: Among all the solar system members, only Earth possesses suitable temperature, air, and water necessary to sustain life.
In simple words: Earth is special because it's the only planet in our solar system with the right temperature, air, and water for life.

Exam Tip: Focus on the unique combination of conditions (temperature, air, water) that makes Earth a habitable planet.

 

Question 2. Which are the major spheres on Earth ?
Answer: There are four major spheres on Earth. They are:
1. Lithosphere
2. Hydrosphere
3. Atmosphere and
4. Biosphere.
In simple words: Earth has four main parts: land (lithosphere), water (hydrosphere), air (atmosphere), and life (biosphere).

Exam Tip: Clearly list all four spheres and try to remember a brief description for each.

 

Question 3. What is Magma ?
Answer: Molten rocks found in the interior of Earth are known as 'Magma'.
In simple words: Magma is melted rock found deep inside Earth.

Exam Tip: Distinguish magma (underground) from lava (above ground, after eruption).

 

Question 4. Why is the crust of Earth not broken ?
Answer: Many gases are present in Earth's interior, which rise up with pressure and heat. However, the pressure from rocks on Earth's surface is equally strong. So, a balance is maintained between the two, and Earth's crust does not break.
In simple words: Earth's crust doesn't break because the strong outward push from hot gases inside is balanced by the strong inward pressure of the rocks on top.

Exam Tip: Explain the balance of forces: upward pressure from internal heat and gases, countered by downward pressure from the crustal rocks.

 

Question 5. Name the oceans on Earth.
Answer: There are four oceans on Earth: They are the Pacific, the Atlantic, the Indian, and the Arctic oceans.
In simple words: The four big oceans on Earth are the Pacific, Atlantic, Indian, and Arctic.

Exam Tip: List the four major oceans accurately.

 

Question 6. Which elements make up atmosphere ?
Answer: Atmosphere is made up of various gases, water vapor, dust particles, salt particles, smoke, micro-organisms, and other components.
In simple words: The atmosphere is made of different gases, water vapor, dust, salt, smoke, and tiny living things.

Exam Tip: When listing components of the atmosphere, include both gaseous (e.g., nitrogen, oxygen) and particulate matter (dust, water vapor).

 

Question 7. Which gases make up atmosphere ?
Answer: Atmosphere is composed of gases like nitrogen, oxygen, carbon dioxide, hydrogen, ozone, and other trace gases.
In simple words: The main gases in the atmosphere are nitrogen, oxygen, carbon dioxide, hydrogen, and ozone.

Exam Tip: Focus on the most common and significant gaseous components of the atmosphere.

 

Question 8. How does ozone gas work ?
Answer: Ozone gas absorbs ultra-violet sunrays and protects the biosphere on Earth from their harmful effects.
In simple words: Ozone gas acts like a shield, blocking dangerous UV rays from the sun and keeping life on Earth safe.

Exam Tip: Emphasize ozone's role in absorbing UV radiation and its protective function for the biosphere.

 

Question 9. Where and when is ozone gas found in greater proportion ?
Answer: Ozone gas is found in greater proportion in the morning in open grounds and in the air near the sea.
In simple words: There's more ozone in the morning in open areas and by the sea.

Exam Tip: Recall that ozone concentration can vary geographically and temporally due to atmospheric conditions and chemical reactions.

 

Question 10. What is meant by 'Condensation'?
Answer: The process of cooling vapor is called 'Condensation'. Various forms of moisture like dew, fog, clouds, and precipitation are seen because of condensation.
In simple words: Condensation is when vapor cools down and turns into liquid, forming things like dew, fog, and clouds.

Exam Tip: Define condensation as the change of state from gas (vapor) to liquid, and list examples of its visible forms.

 

Question 11. How are dust particles in the atmosphere useful?
Answer: Dust particles in the atmosphere spread sunlight in all directions. Because of these particles, it does not suddenly become dark after sunset, nor does it immediately get bright after sunrise.
In simple words: Dust particles in the air scatter sunlight, making dawn and dusk gradual instead of sudden.

Exam Tip: Explain that dust particles cause the scattering of light, contributing to twilight phenomena and the overall illumination of the atmosphere.

 

Question 12. Why are radio and television transmissions possible ?
Answer: Sound is heard only in the presence of atmosphere. Radio and television transmissions are only possible because of the atmosphere.
In simple words: Radio and TV signals can travel and be heard because Earth has an atmosphere.

Exam Tip: The atmosphere plays a crucial role in the propagation of electromagnetic waves used for broadcasting, and sound also requires a medium to travel.

 

Question 13. What are the divisions of biosphere? What do they include?
Answer: There are two main divisions of the biosphere: Living (Biotic) and Non-living (Abiotic). The biotic division includes human beings, vegetation, animals, and tiny insects. The lithosphere, hydrosphere, and atmosphere are included in the abiotic division.
In simple words: The biosphere is split into two parts: living things (like people, plants, and animals) and non-living things (like land, water, and air).

Exam Tip: Clearly differentiate between the biotic (living) and abiotic (non-living) components of the biosphere, and provide examples for each.

 

Question 14. Which human activities affect the lithosphere adversely ?
Answer: Human activities like intense mining for minerals, underground nuclear testing, deep drilling to obtain mineral oil, and tube wells, among others, negatively affect the lithosphere.
In simple words: Human actions such as heavy mining, nuclear tests underground, deep oil drilling, and using tube wells harm the Earth's land (lithosphere).

Exam Tip: List specific human activities that cause direct physical disruption or pollution to the Earth's crust.

Answer the Following Questions:

 

Question 1. How did the four spheres come into existence on Earth?
Answer: Our planet started as a massive fiery ball that slowly cooled over time. Different parts on Earth changed into solids, liquids, gases, or even living organisms during this process. These changes led to the formation of the Earth's four main spheres: (1) Lithosphere, (2) Hydrosphere, (3) Atmosphere, and (4) Biosphere. The solid land elements on the Earth's surface became the 'Lithosphere'. Liquid elements formed the 'Hydrosphere'. Elements that became gases are known as the 'Atmosphere', and the developing world of living things is called the 'Biosphere'.
In simple words: Earth began as a hot ball of fire. As it cooled, things changed into solid, liquid, gas, and life. These became the four main parts of Earth: land, water, air, and living things.

Exam Tip: To explain the formation of Earth's spheres, describe its initial state and how different materials transformed over time, explicitly naming each sphere and its origin.

 

Question 2. Explain the importance of lithosphere.
Answer: The lithosphere is the solid outer part where we live. The word 'Litho' signifies 'Rock', and 'Sphere' means 'layer'. This shell covers about 29% of the Earth's area and measures roughly 64 km to 100 km in thickness. We find different landforms here, such as mountains, high plains, flatlands, and low areas. The lithosphere helps us in various ways. It provides a home for people, gives us room to build houses, and offers clean water and ground for growing crops. It also provides forests and valuable natural resources for manufacturing.
In simple words: The lithosphere is the hard land we live on. It covers about 29% of Earth. It gives us space for houses, farms, forests, and important minerals.

Exam Tip: When explaining the lithosphere's importance, remember to define it, mention its coverage and thickness, and list its key benefits for human life and activities.

 

Question 3. State the uses of hydrosphere.
Answer: The liquid part of Earth is known as the 'Hydrosphere'. It includes vast bodies of water like oceans, smaller seas, inlets, channels, lakes, small pools, and flowing streams. The hydrosphere covers approximately 71% of the Earth's surface. Its uses include:

• Hydrosphere gives us clean drinking water.
• A large portion of the rainfall we receive originates from the hydrosphere.
• Important chemicals and essential minerals are acquired from oceans and seas.
• Many different types of water-based life are supported by oceans and seas.
• Salt is extracted from sea water.
• The powerful movement of waves, ocean tides, and deep sea flows can be used to create electricity.
• Oceans are also valuable as routes for travel and trade.

In simple words: The hydrosphere is all the water on Earth. It gives us fresh water, and most rain comes from it. We get useful chemicals and salt from oceans. It also supports sea life, can make electricity, and serves as travel paths.

Exam Tip: When listing the uses of the hydrosphere, remember to highlight its critical role in providing water, supporting life, offering resources, and enabling transportation.

 

Question 4. State the uses of atmosphere.
Answer: The layer of air that surrounds the Earth is known as the 'Atmosphere'. It reaches up to approximately 1600 km from the Earth's surface and is invisible to the unaided eye. Key benefits of the atmosphere are:

• Atmospheric oxygen is vital for all living beings on our planet.
• Nitrogen is crucial for the development of plant life.
• Carbon dioxide serves as a nutrient for green plants.
• Nitrogen lowers the strength of oxygen.
• Ozone gas takes in harmful ultraviolet sunrays, thereby shielding Earth from the sun's extreme warmth. Ozone also acts as a refreshing gas.
• Dust particles in the atmosphere help scatter sunlight in every direction. This prevents sudden darkness after sunset and immediate brightness after sunrise. These particles reflect sunrays, which helps us get sunlight, and also contribute to cloud formation.
• Sound can only be heard because of the atmosphere. Radio and television transmissions are only achievable due to the atmosphere.

In simple words: The atmosphere is the air around Earth. It gives us oxygen to breathe and nitrogen for plants. Carbon dioxide helps plants grow. Ozone protects us from the sun's harmful rays. Dust particles spread sunlight, and we can hear sounds and use radio/TV because of the atmosphere.

Exam Tip: When listing the uses of the atmosphere, remember to include the roles of different gases (oxygen, nitrogen, carbon dioxide, ozone), dust particles, and its importance for sound and communication.

 

Question 5. Which human activities affect the hydrosphere adversely ?
Answer:

• Oil leaks from boats.
• Throwing industrial and chemical waste into rivers, small streams, lakes, and oceans contaminates the water and harms sea creatures. This poses a significant threat to the hydrosphere.
• The ice at the Earth's poles has begun to melt because of rising temperatures.

In simple words: Human actions that harm the hydrosphere include oil spills from ships, dumping factory waste and chemicals into water bodies, and the melting of polar ice caps due to global warming.

Exam Tip: When discussing adverse human impacts on the hydrosphere, focus on pollution sources like oil and waste, and environmental changes such as melting ice caps.

 

Question 6. Which human activities pollute the atmosphere and what are the effects?
Answer: The natural equilibrium of Earth's different spheres has been upset by human actions, whether intentional or not, for progress and growth. Things like atomic testing, too much drilling for crude oil or borewells, disposing of refuse, and letting out smoke from factories and vehicle exhaust all contaminate Earth's surrounding layers. The rise in global temperatures has caused the polar ice to melt, and deforestation from careless tree cutting has negatively impacted rainfall patterns. All these actions harm the biosphere. The amount of carbon dioxide (\(CO_2\)) in the air has risen, leading to more global warming.
In simple words: Human activities like nuclear tests, drilling, waste dumping, and vehicle exhaust pollute the atmosphere and other parts of Earth. These actions cause polar ice to melt, change rainfall, and increase carbon dioxide, leading to more global warming.

Exam Tip: When explaining atmospheric pollution by humans, mention various activities like industrial emissions and deforestation, and their consequences such as global warming and altered climate patterns.

Write Short Notes:

 

Question 1. Lithosphere
Answer: The solid outermost shell where we exist is called the lithosphere. The term 'Litho' refers to 'Rock', and 'Sphere' indicates 'layer'. This layer covers about 29% of the Earth's total area and ranges from approximately 64 km to 100 km in thickness. Various topographical features such as mountains, elevated flat areas, vast flatlands, and depressions are visible on the lithosphere. Moving closer to the Earth's core, the heat gradually rises. Rocks found inside the Earth that are in a melted state are known as 'Magma'. Numerous gases within the core move upwards due to intense pressure and heat. However, the weight of the rocks on the Earth's exterior surface is equally powerful, ensuring a stable equilibrium so the Earth's outer layer remains unbroken. If this balance is upset, the crust can fracture, leading to volcanic eruptions. The lithosphere serves many purposes. It provides a habitat for people. It offers areas for building residences, getting potable water, and cultivating land, in addition to forests and valuable natural resources for manufacturing.
In simple words: The lithosphere is the hard, rocky part of Earth's surface where we live. It covers about 29% of Earth and is 64-100 km thick. It includes mountains, plains, and valleys. Inside Earth, hot, melted rock is called magma. Gases and rock pressure usually stay balanced, keeping the crust solid. But if this balance breaks, volcanoes can erupt. The lithosphere gives us a home, water, land for farms, forests, and minerals.

Exam Tip: For a short note on the lithosphere, define it, state its composition, thickness, and key features. Also, briefly explain its internal dynamics (magma, pressure) and its importance for human life and resources.

 

Question 2. Hydrosphere
Answer: The liquid portion of Earth is known as the 'Hydrosphere'. It consists of large water bodies like oceans, smaller seas, inlets, narrow channels, lakes, small pools, and flowing rivers. The hydrosphere makes up approximately 71% of the Earth's exterior. A very large body of water is called an 'Ocean'. The four main oceans on Earth - Pacific, Atlantic, Indian, and Arctic - are all connected. These oceans are incredibly vast and profound, with underwater trenches that can be 10 to 11 km deep. The ocean floor also has features similar to land, such as mountains, elevated areas, wide flatlands, and depressions. Oceans hold about 97% of Earth's water, and roughly one-third of the remaining water is stored in ice caps and glaciers. Only a small amount of water gathers in lakes, some moves through rivers, and a portion is stored underground. The quantity of drinkable water, or fresh water, is quite limited. Because fresh water is valuable, it must be used cautiously and not wasted. Life cannot continue without fresh drinking water. Water vapor for rain, which is the primary source of fresh water, originates from oceans. Important chemicals, marine animals, salt, and other minerals are acquired from seas and oceans. Many diverse forms of aquatic life are supported in oceans and seas. The immense power of waves, ocean tides, and deep-sea currents offers a possible way to produce electricity. Oceans also serve as important travel routes.
In simple words: The hydrosphere is all the water on Earth, covering about 71% of its surface. This includes oceans, seas, lakes, and rivers. Oceans are vast and deep, holding 97% of Earth's water. Most fresh water is trapped in ice or underground, so drinkable water is scarce and must be saved. Oceans provide rain, minerals, and support diverse sea life. The power of ocean movements can make electricity, and oceans are also used for travel.

Exam Tip: For a detailed note on the hydrosphere, define it, state its coverage, list its components, and elaborate on its importance, including water distribution, resources, and ecological roles.

 

Question 3. Atmosphere
Answer: The layer of air that completely surrounds our planet is known as the 'Atmosphere'. It reaches approximately 1600 km above the Earth's surface and is not visible to the human eye. The atmosphere is composed of various gases such as nitrogen, oxygen, carbon dioxide, ozone, hydrogen, water vapor, tiny dust particles, smoke, salt bits, and very small living things, making it clear, scentless, and transparent. The air contains about 78% nitrogen, 21% oxygen, and 1% other gases. The concentration of these gases decreases as one moves further from the Earth's surface. Heavier gases like carbon dioxide are more common in the lower parts of the air. Ozone gas makes up a small part of the atmosphere. This gas absorbs the Sun's harmful ultraviolet rays, thereby shielding Earth from extreme solar heat. This gas is found in higher amounts in the mornings in open areas or near coastal regions. Both oxygen and nitrogen are essential gases that support life on Earth. Nitrogen helps to lessen the strength of oxygen. Water is a very important part of the atmosphere; it evaporates due to warmth and stays in the air as water vapor. The process where water vapor cools and turns back into liquid is called 'Condensation'. Different forms of moisture, like dew, mist, clouds, and rain, occur because of condensation. The atmosphere influences many parts of human existence, including what we eat, what we wear, where we live, our skin color, and how we earn money. The dust particles in the atmosphere show that sunlight spreads in all directions. Because of these dust particles, it doesn't get dark suddenly after the sun sets, nor does it become bright immediately after sunrise. These particles bounce sunlight onto Earth's surface, allowing us to receive solar illumination. Sound can only be heard when the atmosphere is present. Radio and television signals can only be sent because of the atmosphere.
In simple words: The atmosphere is the invisible layer of air around Earth, reaching about 1600 km high. It contains gases like nitrogen (78%), oxygen (21%), carbon dioxide, and ozone, plus dust and water vapor. Ozone protects us from harmful sun rays. These gases are vital for life. Water in the atmosphere causes rain and clouds through condensation. Dust particles help spread sunlight, preventing sudden changes from day to night. The atmosphere is also why we can hear sounds and have radio and TV broadcasts.

Exam Tip: For a comprehensive note on the atmosphere, define its composition and extent. Detail the roles of key gases (oxygen, nitrogen, ozone, carbon dioxide), explain condensation, and highlight its significance for light, sound, and communication.

 

Question 4. Biosphere
Answer: The biosphere is the region where living things exist, covering parts of the lithosphere, hydrosphere, and atmosphere. This is a very significant sphere on Earth because our planet is the only one in the solar system with a biosphere. The biosphere contains people, animals, plants, and tiny insects. Human survival relies on the biosphere, as we acquire nourishment and many other essential items from it. We cannot exist without plants or animals; therefore, the biosphere forms the foundation of our life. The biosphere is separated into two main parts:

• Non-living (Abiotic) elements.
• Living (Biotic) components.

The non-living or abiotic part consists of the lithosphere, hydrosphere, and atmosphere. The living or biotic part includes tiny organisms, plant life, and animals.
In simple words: The biosphere is the part of Earth where life exists, including parts of the land, water, and air. Earth is special because it's the only planet with a biosphere. It includes humans, animals, plants, and tiny insects. We depend on the biosphere for food and everything else we need to live. It's divided into non-living (abiotic) parts like land, water, and air, and living (biotic) parts like microbes, plants, and animals.

Exam Tip: For a short note on the biosphere, define its extent, emphasize its uniqueness in the solar system, list its components (living and non-living), and explain its crucial role in sustaining human and other life.