Natural Resources – Air, Water and Land - Standard 6 - General Science - Balbharati
Natural Resources – Air, Water and Land
Exercise
Q.1 Fill in the blanks.
(a) The layer of ozone gas absorbs ultraviolet rays that come from the sun to the earth.
(b) Of the total water available on the earth, fresh water forms 0.3 percent.
(c) Both abiotic and biotic constituents are present in the soil.
Q.2 Why is it said that –?
(a) The ozone layer is a protective shell of the earth.
Ans. The ozone layer is like a protective shield around the Earth. It absorbs harmful UV rays from the sun, keeping us safe from their harmful effects. It plays an important role in protecting all living organisms on our planet.
(b) Water is life.
Ans. Living organisms cannot survive without water. The blood of animals and the sap of plants also have a high proportion of water. Therefore water is said to be life.
(c) Seawater is useful even though it is not potable.
Ans. Even though we can't drink seawater, it is still very useful in many ways:
1. Home for Marine Life: Seawater provides a habitat for many different sea creatures, like fish and coral reefs. It supports a whole ecosystem of marine life.
2. Food Source: The ocean is where we get a lot of our seafood from. Fish and other edible creatures live in seawater, and they provide us with food.
3. Industrial Uses: Seawater is used in industries for things like cooling machinery and extracting valuable resources from the ocean.
4. Fun Activities: Seawater is perfect for activities like swimming, surfing, and boating. People love spending time in the ocean for recreation and tourism.
5. Climate Regulation: The ocean helps regulate the Earth's climate by absorbing heat and influencing weather patterns.
Even though we can't drink it, seawater is still essential for life and serves many important purposes.
Q.3 What will happen if –
(a) Microbes in the soil get destroyed.
Ans. If the tiny organisms called microbes in the soil are destroyed, it would be really bad for the soil. These microbes help the soil stay healthy and fertile. They break down old plants and recycle nutrients. Without them, the soil would become less rich, making it hard for plants to grow and causing problems for farming and nature.
(b) The number of vehicles and factories in your surroundings increases.
Ans. If there are more cars and factories around us, it can create big problems. The air we breathe would get dirtier because of all the pollution from cars and factories. This pollution can make us sick, especially our lungs, and make climate change worse. We need to find ways to make less pollution and use cleaner ways to travel and make things.
(c) The total supply of potable water is finished.
Ans. If we use up all the clean water we can drink, it would be a really serious problem. We need clean water for drinking, cooking, washing, and growing food. Without enough clean water, it would be hard for us to stay healthy, find enough food, and have enough water for everyone. That's why it's important to be careful with our water and not waste it.
Q.4 Match the following.
| Group 'A' | Ans. |
|---|---|
| (1) Carbon | Plants and food production |
| (2) Oxygen | Combustion |
| (3) Water | Rain |
| (4) Microbes | Generation of soil |
Q.5 Name the following.
(a) Constituents of the biosphere
Ans. Animals and plants.
(b) Biotic constituents of soil
Ans. microbes, insects, rodents like rats and mice.
(c) Fossil fuel
Ans. Petrol, Diesel, Kerosene.
(d) Inert gases in air
Ans. Argon, Helium, Neon, Krypton, Xenon.
(e) Gases that are harmful to the ozone layer
Ans. Chlorofluorocarbons, Carbon Tetrachloride.
Q.6 True or false?
(a) Land and soil are the same thing.
Ans. False.
(b) The water in a lake is called groundwater.
Ans. False.
(c) It takes about 1000 years to form a 25 cm thick layer of soil.
Ans. False.
(d) Radon is used in decorative lights.
Ans. False.
Q.7 Answer in your own words.
(a) Explain with the help of a diagram how soil is formed.
Ans.
| Natural Process |
| ↓ |
| Weathering of bedrock (Heat, Cold, Water) |
| ↓ |
| Breakdown of bedrock into pieces |
| ↓ |
| Formation of stones, sand, and soil |
| ↓ |
| Presence of microbes, worms and insects |
| ↓ |
| Presence of Rodents (Mice and Rats) |
| ↓ |
| Trees' roots help in weathering of rock |
| ↓ |
| Soil formation complete. |
The soil on the land is formed by a natural process. The abiotic components of soil are
supplied through the weathering of the bedrock. Due to the heat, cold and water of the sun,
wind and rain respectively, the bedrock breaks down into pieces. Stones, sand and soil are
formed from these pieces. Microbes, worms and insects are found among them. Rodents
like mice and rats are also found here. The roots of trees growing on the land also help
weathering of rocks. The process of soil formation is slow and continuous. It takes about
a thousand years for a 2.5 cm thick layer of mature soil to form.
(b) Why is there a shortage of water even though it occupies about 71% of the earth’s surface?
Ans. We cannot use all the water on earth because seawater is salty which is 97% of the total water. Some water is in a frozen state. A very small quantity of water that is 0.3% is available for drinking. Therefore, there is a shortage of water even though it occupies about 71% of the earth’s surface.
(c) What are the various constituents of air ? Write their uses.
Ans. A] Constituents of air:
1. Nitrogen makes up the largest portion of the Earth's atmosphere, accounting for about 78% of the air we breathe.
2. Oxygen is the second most abundant component of the atmosphere, comprising approximately 21% of the air.
3. Argon is a noble gas that makes up around 0.9% of the air. It is chemically inert and does not readily react with other elements.
4. Carbon dioxide is present in the atmosphere, with a proportion of about 0.03%.
5. Inert Gases and other constituents: These include Neon, Helium, Methane, Ozone, Water vapour, and various pollutants such as sulfur dioxide and nitrogen oxides.
B] Uses of the constituents of air:
• Nitrogen – Helps living things to build the necessary proteins. It is useful in the production of ammonia and in airtight packaging of foodstuffs.
• Oxygen – Necessary for respiration in living things and for combustion.
• Carbon dioxide – Plants use it for producing their food. Used in fire extinguishers.
Argon – Used in electric bulbs.
• Helium – Used for obtaining low temperature and also for generating lift in airships.
• Neon – Used in decorative lights and for street lighting.
• Krypton – Used in fluorescent tubes.
• Xenon – Used in flash photography.
(d) Why are air, water and land considered to be valuable natural resources?
Ans. Air, water, and land are important because they help us stay alive, provide things we need, and keep nature healthy. We need clean air to breathe, water to drink and grow crops, and land for homes and food. They are valuable because they give us what we need to live and make Earth a good place to be.
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