01 Natural Resources - Air, Water and La carbon dioxide, ... Summative Assessment Q b. ... Natural Resources: Air, Water and Land ...

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<ul><li><p>z </p><p>Chapter 1: Natural Resources: Air, Water </p><p> and Land </p><p>1 </p><p>Lets Revise</p><p>1. Natural Resources: i. The elements available in the nature that fulfill the basic needs of living things on </p><p>earth, thereby allowing life to sustain on earth are known as Natural Resources. </p><p> ii. Air, water and land are called the earths atmosphere, hydrosphere and lithosphere respectively. </p><p> iii. Living things and the parts of the lithosphere, hydrosphere and atmosphere which they occupy are together called as biosphere (In Greek, bios = life, </p><p>sphaira = sphere). </p><p>2. Air: </p><p> i. Air in the atmosphere around the earth comprises of various gases such as nitrogen, </p><p>oxygen, carbon dioxide, six inert gases, nitrogen dioxide, sulphur dioxide, water </p><p>vapour and dust particles. </p><p> ii. Proportion of gases in air is as follows: </p><p>Spheres of Earth Proportion of gases </p><p>Troposphere 80% of the total mass of gases in the air </p><p>Stratosphere 19% of the total mass of gases in the air </p><p>Mesophere and Ionosphere Proportion of gas goes on decreasing </p><p>Exosphere Lacks gases completely </p><p> iii. Uses of the different gases in air are as follows: </p><p>Gas Uses </p><p>Nitrogen </p><p>Helps living things to build necessary proteins. </p><p>Useful in production of ammonia also, in food industry for air </p><p>tight packaging of food items. </p><p>Oxygen Essential for respiration (breathing in living things) and for </p><p>burning (combustion). </p><p>Carbon dioxide For photosynthesis (in plant) and is a major constituent of fire </p><p>extinguishers. </p><p>Argon Used in electric bulbs. </p><p>Helium Used for obtaining low temperature and for generating lift in </p><p>airships. </p><p>Neon Used in street lights and decorative lights. </p><p>Krypton Component of fluorescent tubes. </p><p>Xenon Used in flash photography. </p><p> iv. Atmosphere acts as an important filter, because: </p><p> a. It allows light and heat to reach earths surface in quantities required for life to </p><p>sustain on earth. </p><p> b. Also, it prevents harmful elements from reaching the earth. </p><p> v. Fog, clouds, snow and rain are produced in atmosphere. </p><p> vi. Air pollution: Any undesirable change in the normal composition of the air by </p><p>addition of harmful gases is known as air pollution. </p><p>1. Natural Resources : Air, Water and Land</p></li><li><p>Std. VI: General Science Workbook </p><p>2</p><p> vii. Air pollution is caused by harmful gases given out through combustion of fuels in </p><p>vehicles and in big industries. It is also caused due to incomplete combustion of fuels </p><p>like coal and wood. </p><p> viii. Nitrogen dioxide, carbon dioxide, carbon monoxide, sulphur dioxide and soot are </p><p>some harmful air pollutants. </p><p>3. Ozone layer: </p><p> i. Ozone layer is present in the lower part of the stratosphere. </p><p> ii. It functions as a shell to protect the earth from harmful ultra violet rays coming from </p><p>the sun. </p><p> iii. Chemical gases like Carbon tetrachloride, Chlorofluorocarbons used in air </p><p>conditioners and refrigerators mix with air and destroy ozone layer. </p><p>4. Water: </p><p> i. It is said that Water is life, because it is absolutely essential for survival of living </p><p>things. </p><p> ii. Water is colourless, tasteless and odourless. It is universal solvent (many substances </p><p>readily dissolves). It occurs in three states such as solid (ice), liquid (water) and </p><p>gaseous (water vapour). </p><p> iii. The blood of animals and sap in plants contain a very high proportion of water. </p><p> iv. Water available on earth: </p><p> a. Water in seas and oceans: 97% </p><p> b. Ground water, frozen state (ice): 2.7% </p><p> c. Fresh, drinking water: 0.3% </p><p> Thus, only 0.3% of total water covering the earths surface can be utilized for the purpose </p><p>of drinking. </p><p>5. Water cycle: </p><p> i. Water cycle that leads to rainfall is the major source of water on earth. </p><p> ii. Water evaporates from the oceans, gets stored in the clouds and condenses as rain. </p><p>Thus, fresh water enters the ocean, thereby completing the cycle. </p><p> iii. Rain water also seeps into the ground, thereby increasing the ground water level. </p><p>This gives rise to other sources of water like rivers, ponds, springs, lakes, streams. </p><p> iv. Uncontrolled use of water for the ever increasing population, industry and farming </p><p>has resulted in shortage of water. </p><p> v. Thus, it is necessary to use water sparingly. Water can be percolated in the ground by</p><p>blocking it. Stored water does not become stale at once, thus it can be reused </p><p>wherever possible. </p><p>6. Land: </p><p> i. Land is seen in the form of stones, soil, big rocks. </p><p>Both plants and animals need land. Humans live on </p><p>land as well as utilize it for other purposes like </p><p>shelter, farming etc. Land is an important source of </p><p>minerals, crude oil and natural gas, which are useful </p><p>for humans in many ways. </p><p> ii. Layers of land: </p><p> a. Humus: Topmost mature layer. It is most </p><p>fertile layer formed by decomposition of </p><p>animals and plants. </p><p>Humus</p><p>Immature soil </p><p>Bedrock</p><p>Top soil</p><p>Layers of land</p><p>Layer of soil and </p><p>small rocks </p></li><li><p>z </p><p>Chapter 1: Natural Resources: Air, Water </p><p> and Land </p><p>3 </p><p> Fill in the blanks </p><p>*1. The layer of ozone gas absorbs --------------------------------</p><p> rays that come from the sun to the </p><p> earth. </p><p>*2. Of the total water available on the earth, fresh water forms --------------------------------</p><p> percent. </p><p>*3. Both --------------------------------</p><p> and --------------------------------</p><p>constituents are present in the </p><p> soil. </p><p>Summative Assessment</p><p>Q</p><p> b. Top soil: Full of sand, soil, small stones, worms and insects. </p><p> c. Immature soil: Comprises of soil and pieces of bedrock. </p><p> d. Bed rock: A layer with less soil and more rocks. Minerals are obtained from this </p><p>layer. Responsible for colour and texture of the soil. </p><p> iii. Soil formation is slow, continuous and </p><p>natural process. It takes about a </p><p>thousand years for a 2.5 cm thick layer </p><p>of mature soil to form. </p><p> iv. Heat, cold and water breakdown the </p><p>bedrocks into pieces. From these </p><p>pieces stones, sand and soil particles </p><p>are formed. </p><p> v. Microbes, worms and insects as well as </p><p>rodents like mice and rats are found </p><p>here. Roots of trees also contribute in </p><p>weathering of rocks. </p><p> vi. Soil erosion occurs due to natural </p><p> calamities like earthquakes, fluids, storms and human activities such as mining, </p><p>farming and deforestation etc. It makes land barren. </p><p> vii. Thus, to prevent soil erosion, it is necessary to plant more trees, as the roots of </p><p>trees/plants/ grasses and bushes hold the soil particles tightly. </p><p> viii. Formation of fossil fuels: Geographical upheavals led to burial of the trees and </p><p>animals deep inside the land. Burial of the remains of plants and animals for many </p><p>ages led to formation of fossil fuels. </p><p> ix. Fossil fuel gives us many useful substances such as petrol, diesel, kerosene, paraffin, </p><p>tar and wax. </p><p> x. All living things utilize the natural resources for their survival but the availability of </p><p>natural resources in the environment is limited. </p><p> For example Oxygen 21% </p><p> Fresh water 0.3% </p><p> Land 29% </p><p> Thus, one need to use these resources judiciously. </p><p> xi. India Meteorological Department (IMD) was established in 1875 for studying the </p><p>weather in Indian subcontinent. </p><p>Stones, Sand, </p><p>Soil </p><p>Breaks down into</p><p>Rock</p><p>Wind Cold</p><p>Formation of </p><p>layer of soil </p><p>Microbes </p><p>Rodents</p><p>Roots of </p><p>plants </p><p>Heat Water </p></li><li><p>Std. VI: General Science Workbook </p><p>4</p><p>4. Atmosphere, hydrosphere and lithosphere constitute the --------------------------------</p><p>. </p><p>5. Gases are absent in --------------------------------</p><p> layer of atmosphere. </p><p>6. Fog, snow and rain are formed in --------------------------------</p><p>. </p><p> Right or Wrong ? If Wrong, write the correct sentence </p><p>*1. Land and soil are the same thing. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>*2. The water in a lake is called ground water. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>*3. It takes about 1000 years to form a 25 cm thick layer of soil. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>*4. Radon is used in decorative lights. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>5. Weathering of rock is the initial process of soil formation. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>6. Hydrosphere occupies 71% of the earths surface. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>7. The land on the earths surface is the lithosphere. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>8. Soil is formed by man-made process. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p> Odd one out </p><p>1. Soot, nitrogen dioxide, carbon monoxide, oxygen, sulphur dioxide. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>2. Petrol, paraffin, diesel, kerosene, chlorofluorocarbon. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p> Q</p><p>Q</p></li><li><p>z </p><p>Chapter 1: Natural Resources: Air, Water </p><p> and Land </p><p>5 </p><p> Match the Following </p><p>*1. Match the natural resources from Group A with the related descriptions given in Group B. </p><p>Group A Answer Group B </p><p>i. Carbon dioxide a. Generation of soil </p><p>ii. Oxygen b. Rain </p><p>iii. Water vapour c. Plants and food </p><p>production </p><p>iv. Microbes d. Combustion </p><p>2. Match the name of the gases from Group A with their uses given in Group B. </p><p>Group A Answer Group B </p><p>i. Xenon a. Used to obtain low </p><p>temperature </p><p>ii. Argon b. Used in fire </p><p>extinguishers </p><p>iii. Helium c. Used in electric bulbs </p><p>iv. Carbon dioxide d. Useful in agriculture </p><p> Answer in one word </p><p>1. Name the following </p><p>*i. Constituents of the biosphere ----------------------------</p><p> ----------------------------</p><p>*ii. Biotic constituents of soil ----------------------------</p><p> ---------------------------- </p><p>*iii. Fossil fuel ----------------------------</p><p>*iv. Inert gases in air ----------------------------</p><p>*v. Gases that are harmful to the ozone layer ----------------------------</p><p>vi. The topmost fertile natural layer of the soil. ----------------------------</p><p>vii. The process of destruction of fertile layer of soil by floods, storm and </p><p>human activities. ----------------------------</p><p>viii. The institute established for studying the weather changes and </p><p>making the forecasts about rainfall in the Indian subcontinent. ----------------------------</p><p>Q</p><p>Q</p></li><li><p>Std. VI: General Science Workbook </p><p>6</p><p> Answer in your own words </p><p>*1. Explain with the help of a diagram how soil is formed. </p><p>Ans: ---------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>---------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>*2. Why is there a shortage of water even though it occupies about 71% of the earths surface? </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>Q</p></li><li><p>z </p><p>Chapter 1: Natural Resources: Air, Water </p><p> and Land </p><p>7 </p><p>*3. What are the various constituents of air? Write their uses. </p><p>Ans: --------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>--------------------------------------------------------------------------------------------------------------------- </p><p>-------------------------------------...</p></li></ul>


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