Q1: In addition to the rock particles, the soil contains:
Q2: In addition to the rock particles, the soil contains:
Q3: Match the items in Column I with those in Column II:
|Column I||Column II|
Ans:1-b, 2-c, 3-a, 4-e, 5-d
Q4: Explain how soil is formed.
Ans: Soil formation Soil is formed from the rocks due to the action of either or some of these processes –
(a)Earthquakes or Volcanic Eruptions: There is a hard layer of rock just below the earth surface. Due to natural processes like earthquakes and volcanic eruptions these big chunk of rocks are broken into smaller pieces and come on the surface of the earth.
(b)Weathering of rocks: due to fast blowing winds, falling of snow, actions of glaciers and running water of rains etc. the fine particles from the surface of rocks are carried away to different places. During this process, which is very slow and takes thousands of years, the sizes of these particles are further reduced. This whole process is called as ‘physical weathering’.
(c)Corrosion or Decomposition of rocks: The smaller particles of rocks obtained due to weathering get further decomposed on long exposure to air and moisture. These processes range from oxidation, reduction, hydration, hydrolysis and carbonation. Lichens and other plants help in the process, e.g. rocks of minerals like feldspar and mica combine with water through the process of hydration and become soft and easily disintegrable. Silicate rocks on hydrolysis produce silicate clays. These are very slow process known as ‘chemical weathering’.
(d) Addition of Humus: Finally the decomposed parts of dead plants and organisms get mixed up with the soil formed above. This gives the soil enough energy in the form of organic matter.
There are other factors also influencing soil formation such as:
3. Parent rocks
Q5: List the difference between clayey soil and sandy soil. Solution:
|Clayey Soil||Sandy Soil|
Q6: Explain how soil pollution and soil erosion could be prevented.
Ans: Prevention of Soil Pollution: Following steps are necessary to prevent the soil pollution –
Prevention of Soil Erosion: Soil erosion can be prevented by taking the following steps –