{"id":25146,"date":"2022-05-20T02:00:43","date_gmt":"2022-05-19T20:30:43","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=25146"},"modified":"2023-11-10T11:10:15","modified_gmt":"2023-11-10T05:40:15","slug":"icse-solutions-for-class-9-geography-weathering","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/icse-solutions-for-class-9-geography-weathering\/","title":{"rendered":"ICSE Solutions for Class 9 Geography – Weathering"},"content":{"rendered":"

ICSE Solutions for Class 9 Geography – Weathering<\/strong><\/span><\/h2>\n

ICSE Solutions<\/a>Selina ICSE Solutions<\/a>ML Aggarwal Solutions<\/a><\/p>\n

Exercises<\/strong><\/span><\/p>\n

I. Short Answer Questions.<\/strong><\/p>\n

Question 1.<\/strong><\/span>
\nWhat is weathering ?
\nAnswer:<\/strong><\/span>
\nWeathering involves disintegration or decay of solid rock due to change in temperature and weather and their impact on the composition of rock.<\/p>\n

Question 2.<\/strong><\/span>
\nGive one point of difference between physical and chemical weathering.
\nAnswer:<\/strong><\/span>
\nPhysical weathering does disintegration of rock without chemical reaction and the chemical weathering does change in chemical compounds within rock.<\/p>\n

Question 3.<\/strong><\/span>
\nWhat is known as exfoliation ? Name the processes involved in it ?
\nAnswer:<\/strong><\/span>
\nSudden change in temperature causes fissures in the rocks through which water penetrates to motivate chemical weathering along with sudden contraction and expansion due to change in temperature peels out the upper layer of rock known as exfoliation.<\/p>\n

Question 4.<\/strong><\/span>
\nName the four processes involved in chemical weathering.
\nAnswer:<\/strong><\/span>
\nThese are solution, carbonation, oxidation and hydration.<\/p>\n

Question 5.<\/strong><\/span>
\nWhat is known as oxidation ?
\nAnswer:<\/strong><\/span>
\nIt is the process of reaction of minerals present in rocks to atmospheric oxygen.<\/p>\n

Question 6.<\/strong><\/span>
\nBriefly describe biological weathering.
\nAnswer:<\/strong><\/span>
\nBiological weathering is done by animals, insects plants and man, because these break up the rocks through making holes, root channels and construction of building, canals etc.<\/p>\n

Question 7.<\/strong><\/span>
\nWhat are exogenic forces ?
\nAnswer:<\/strong><\/span>
\nThese are the external forces that sculpture the surface features of the land.<\/p>\n

Question 8.<\/strong><\/span>
\nWhat is called denudation ? Name the processes involved in it.
\nAnswer:<\/strong><\/span>
\nDenudation is the wearing away of landmass by various agents as water, wind and ice through various processes like weathering, mass movement, erosion and transportation.<\/p>\n

Question 9.<\/strong><\/span>
\nName the two processes of gradation.
\nAnswer:<\/strong><\/span>
\nTwo processes are denudation and aggradation.<\/p>\n

Question 10.<\/strong><\/span>
\nWhat is the chief characteristic of weathering in tropical climates ?
\nAnswer:<\/strong><\/span>
\nTropical climates are noted for distinct dry and wet season and high rate of evaporation. During rainy season the oxides of iron and aluminium are dissolved in water and mix up with the soil to form laterite soils.<\/p>\n

Question 11.<\/strong><\/span>
\nWhat is known as mass wasting ?
\nAnswer:<\/strong><\/span>
\nThe movement of loose material derived from the bed rock through weathering is called mass wasting.<\/p>\n

Question 12.<\/strong><\/span>
\nName any two slow movements of mass wasting.
\nAnswer:<\/strong><\/span>
\nSlow movements of mass wasting an be divided into two
\nmain types \u2014 Creep and Solifluction.
\nCreep :\u00a0<\/strong>The slow downhill movement of debris is called soil creep.
\nSolifluction :\u00a0<\/strong>The water mixed with soil forms clay which moves as a thick viscous fluid.<\/p>\n

Question 13.<\/strong><\/span>
\nGive one example of rapid mass movement.
\nAnswer:<\/strong><\/span>
\nRapid mass movement includes large amount of debris, soil, boulders and rock pieces etc, e.g. landslides and sheet erosion or displacement of the upper rock strata in large amount to uncover the rocks lying below.<\/p>\n

Question 14.<\/strong><\/span>
\nWhat is known as Sheet Wash ?
\nAnswer:<\/strong><\/span>
\nIt is the rapid movement of rock debris etc in heavy amount taking the form of a thick sheet of thick fluid of soil and clay removing settlement and vegetation cover, too.<\/p>\n

II. Give a technical term for each of the following :<\/strong><\/p>\n

Question 1.<\/strong><\/span>
\nDisintegration or decomposition of rock.
\nAnswer:<\/strong><\/span>
\nWeathering.<\/p>\n

Question 2.<\/strong><\/span>
\nPeeling off of the outer layer of rock through contraction and expansion.
\nAnswer:<\/strong><\/span>
\nExfoliation<\/p>\n

Question 3.<\/strong><\/span>
\nExpansion of minerals in rocks on coming into contact with rainwater.
\nAnswer:<\/strong><\/span>
\nHydration.<\/p>\n

Question 4.<\/strong><\/span>
\nThe leveling of land surface by erosion and deposition.
\nAnswer:<\/strong><\/span>
\nGradation.<\/p>\n

Question 5.<\/strong><\/span>
\nThe process in which a landform of lower level is upgraded to a higher level.
\nAnswer:<\/strong><\/span>
\nAggradation.<\/p>\n

III. Say whether the following are \u2018True\u2019 or \u2018False\u2019.<\/strong><\/p>\n

1.<\/strong> Temperature is not a factor in physical weathering.
\nAnswer.<\/strong> False<\/p>\n

2.<\/strong> In dry climates mechanical weathering is dominant.
\nAnswer.<\/strong> True<\/p>\n

3.<\/strong> In Polar regions there is no chemical weathering.
\nAnswer.<\/strong> True<\/p>\n

4.<\/strong> External forces are engaged only in erosion.
\nAnswer.<\/strong> False<\/p>\n

5.<\/strong> Shear plane is the surface on which movement of a landslide takes place as a result of its breaking off.
\nAnswer.<\/strong>True<\/p>\n

IV. Long Answer Questions.<\/strong><\/p>\n

PQ. Describe the process of denudation and gradation.<\/strong>
\nAnswer:<\/strong><\/span>
\nDenudation is the process of wearing away of rock-strata by water, wind and ice along with change in weather and temperature.
\nGradation is the process of leveling down the whole landform gradually to ground level by various agents of change mainly water, (rivers), wind and ice (glaciers), etc.<\/p>\n

Question 1.<\/strong><\/span>
\nDefine weathering and describe the chief characteristics of weathering.
\nAnswer:<\/strong><\/span>
\nWeathering is the process of breaking down of rocks but not its removal. It is described as disintegration or decomposition of a rock in size by natural agents at or near the surface of the earth.
\nChief characteristics of weathering<\/strong> are disintegration of rocks, chemical change in rocks, change in the surface of land, formation of soil, several processes involved in weathering like temperature and weather change and reactions, transportation of rock material from one place to another resulting in formation of large plains like Northern plain of India.<\/p>\n

Question 2.<\/strong><\/span>
\nDistinguish between physical and chemical weathering.
\nAnswer:<\/strong><\/span>
\nPhysical Weathering :<\/strong><\/p>\n

    \n
  1. Rock disintegration without any change in chemical constituents of rocks takes place.<\/li>\n
  2. Factors such as temperature, moisture, pressure cause physical break-up of rocks.<\/li>\n
  3. It takes place in hot dry and cold areas due to rapid temperature changes.<\/li>\n
  4. Rocks are affected to great depths.<\/li>\n
  5. Its agents are temp erature and moisture.<\/li>\n<\/ol>\n

    Chemical Weathering :<\/strong><\/p>\n

      \n
    1. Mineral in rocks are dissolved or altered.<\/li>\n
    2. Temperature, moisture, etc., cause minerals in rocks to dissolve in water or convert them into other minerals.<\/li>\n
    3. It takes place in hot and humid areas due to chemical action of minerals in rocks.<\/li>\n
    4. It mostly takes place near the surface of the earth.<\/li>\n
    5. Its agents are solution, oxidation, carbonation and hydration.<\/li>\n<\/ol>\n

      Question 3.<\/strong><\/span>
      \nDescribe chemical weathering mentioning the processes involved in it.
      \nAnswer:<\/strong><\/span>
      \nChemical weathering takes place with the help of agents as water, wind and various organic acids, reacting in the chemical composition of rocks which are then disintegrated. Four main processes are solution by dissolving salts in the rocks with water, carbonation works with the reaction of carbon dioxide with rocks, oxidation takes place through atmospheric oxygen reacting with minerals present in rocks, hydration is evident by mixing of rainwater with minerals in rocks, which expand by this and become heavy.<\/p>\n

      Question 4.<\/strong><\/span>
      \nWhat is biological weathering ? State the main agents of biological weathering.
      \nAnswer:<\/strong><\/span>
      \nBiological weathering is weathering caused by plants and animals. Plants and animals release acid forming chemicals that cause weathering and also contribute to the breaking down of rocks and landforms. It is also known as Organic weathering. Its main agents are animals, insects, plants and man. In all the cases, however, both physical disintegration and \/ or chemical decomposition are involved. Their role can be explained as follows :<\/p>\n

        \n
      1. Animals and Insects :<\/strong> Animals like rabbits, worms, moles and insects bring large quantities of fine material to the surface. Burrowing animals help to loosen the surface materials around the rocks facilitating their physical disintegration. Upon death, the decaying physical also provide many chemicals and acids for rock disintegration.<\/li>\n
      2. Vegetation :<\/strong> Roots of large trees reach deep into rocks and cause physical disintegration due to pressure. Most of : vegetation, however, prevents disintegration of rocks because it binds the surface layer and does not allow exposure of rocks beneath to the elements of weathering.<\/li>\n<\/ol>\n

        Question 5.<\/strong><\/span>
        \nDescribe the chief characteristics of weathering in different climates.
        \nAnswer:<\/strong><\/span>
        \nEquatorial region is noted for more active chemical weathering due to excess of temperature and water ; tropical region is remarkable for formation of laterite soil by mixing of oxides of iron and aluminium in the soil due to change in heating and much evaporation.<\/p>\n

        Question 6.<\/strong><\/span>
        \nState and explain the classification of mass movements.
        \nAnswer:<\/strong><\/span>
        \nMass movements are divided into slow and rapid movements. Slow movement includes Creep, movement of soil and debris and Solifluction or clay formation Rapid movement includes landslide, Earth Flow or heavy thick paste of soil down the slope, Mud Flow in the areas without vegetation cover and Sheet Wash in the form of large sheet flow snatching a thick rock strata uncovering the rocks below. It may also take place by human activities of settlement.
        \nMass movement has built many remarkable landforms as Himalayan lakes, Terraces, escarpment etc.<\/p>\n

        Practice Questions (Solved)<\/strong><\/span><\/p>\n

        Question 1.<\/strong><\/span>
        \nName two processes involved in denudation.
        \nAnswer:<\/strong><\/span>
        \nWeathering and Erosion.<\/p>\n

        Question 2.<\/strong><\/span>
        \nWhat does the term denude mean ?
        \nAnswer:<\/strong><\/span>
        \nTo lay the rocks bare.<\/p>\n

        Question 3.<\/strong><\/span>
        \nWhat is weathering ?
        \nAnswer:<\/strong><\/span>
        \nBreaking up of rocks by agents related to atmosphere.<\/p>\n

        Question 4.<\/strong><\/span>
        \nName the gases involved in the process of chemical weathering.
        \nAnswer:<\/strong><\/span>
        \nWeak acids, oxygen, carbon dioxide, hydrogen.<\/p>\n

        Question 5.<\/strong><\/span>
        \nIn which region underground water is an effective agent of denudation.
        \nAnswer:<\/strong><\/span>
        \nUnderground water is an effective agent of denudation in limestone regions.<\/p>\n

        Question 6.<\/strong><\/span>
        \nName few well known physical features caused by chemical weathering.
        \nAnswer:<\/strong><\/span><\/p>\n

          \n
        1. Limestone and chalk landforms of Karst region of Yugoslavia.<\/li>\n
        2. Weathering of granite rocks in Malaysia.<\/li>\n<\/ol>\n

          Question 7.<\/strong><\/span>
          \nWhy is mechanical weathering also known as physical weathering ?
          \nAnswer:<\/strong><\/span>
          \nBecause it involves physical disintegration of rocks. Physical disintegration is quickest when rock is already weakened by chemical weathering. So it is primarily known as mechanical weathering.<\/p>\n

          Question 8.<\/strong><\/span>
          \nWhat is weathering ? Illustrate the process graphically.
          \nAnswer:<\/strong><\/span>
          \nThe break-down but not removal of rocks is called weathering. It is a process of wearing away of land through forces of nature like weather, running water, ocean currents etc. Weathering is a single process and takes place in air.<\/p>\n

          Question 9.<\/strong><\/span>
          \nDistinguish between :<\/strong><\/p>\n

            \n
          1. Weathering and Denudation<\/strong><\/li>\n
          2. Loess and Alluvium.<\/strong><\/li>\n<\/ol>\n

            Answer:<\/strong><\/span><\/p>\n

              \n
            1. Weathering and Denudation :<\/strong> Weathering is a process 4 of gradual disintegration of rocks by atmospheric or weather forces. Denudation is a process of wearing away of land and it includes weathering also.<\/li>\n
            2. Loess and Alluvium :<\/strong> Alluvial soils are formed by depositional activity of running water and loess by wind. Alluvium contains high mineral and humus content, and loess is highly permeable.<\/li>\n<\/ol>\n

              Question 10.<\/strong><\/span>
              \nOn what factors does the weathering depend ?
              \nAnswer:<\/strong><\/span>
              \nWeathering depends upon :<\/strong><\/p>\n