DAV Class 8 SST Chapter 2 Question Answer Natural Resources Land Soil and Water

DAV Class 8 SST Chapter 2 Natural Resources Land Soil and Water Solutions

A. Tick the correct option.

1. Which type of erosion leads to desertification?

Answer: soil erosion

2. Which one of the following is suitable for restoring soil fertility?

Answer: contour ploughing/rotation of crops

3. Which of the following is not in favour of multipurpose river valley projects?

Answer: large scale displacement of people

4. Maintenance of lakes and ponds is essential for-

Answer: increasing water table

5. Which factor is more responsible for the quick formation of soil in Rajasthan?

Answer: extreme difference in day and night temperature

B. Fill in the blanks.

1. Earth’s surface is divided into ___________ and ___________ zones.

2. To maintain ecological balance, ___________ % of the land should be under forest.

3. Planting of trees is commonly known as ___________.

4. The main source of fresh water is ___________.

5. Earth is known as ___________ planet due to the presence of water on it.

Answer: (1) land, water (2) 33 (3) afforestation (4) rainfall (5) blue.

C. Write a technical term or an appropriate word for each of the following statements.1. It is formed by decomposed parts of plants and animals.

Answer: Humus

2. The original rock from which the soil is formed.

Answer: Parent rock

3. It is formed as a result of long continued weathering process of rocks.

Answer: Soil

4. A project which serves various purposes at the same time.

Answer: Multipurpose River vally project

5. The process in which the top layer of the soil is removed by the natural and human activities.

Answer: Soil erosion

D. Answer the following questions in brief.

1. Why is soil considered an important resource? Give any three reasons.

Answer: Soil is considered an important resource because:

• Soil is very important for the growth of plants.
• It gives shelter to insects and animals
• Soil is used for making bricks.

2. Highlight any three causes of soil erosion.

Answer: Three causes of soil erosion are:

• Deforestation
• Mining
• Overgrazing of animals.

3. Explain the hydrological cycle with the help of a diagram.

Answer: The hydrological cycle includes the process of evaporation, condensation, and precipitation. The heat of the Sun evaporates water resulting in the formation of water vapour. When the water vapor cools down, it condenses and forms clouds. It is from clouds that the water precipitates in the form of rainfall, snow, etc. The process by which water keeps on changing its form and circulates between the oceans, the atmosphere, and land is known as the hydrological cycle.4. How does river water get polluted? Explain.

Answer: River water gets polluted by:

• Untreated sewage.
• Animal bath in the rivers.
• Dumping waste material into the rivers.

5. Identify any three ecological problems caused by building large dams.

Answer: Three ecological problems caused by building large dams are:

• Aquatic life is affected.
• River water gets diverted.
• The population gets displaced.

E. Answer the following questions.

1. Explain any five factors responsible for the formation of soil.

Answer: Five factors responsible for the formation of soil are the parent rock, the topography, the climate, the vegetation cover, and time.(i) Parent rock – the original rock from which soil is formed is known as the parent rock for example the black soil is derived from the lava rock.

(ii) Topography- Topographical variations, such as mountains, plateaus, and plains affect the thickness of a soil cover.

(iii) Climate – Climatic factors, like temperature and rainfall, affect soil formation. In areas of high rainfall and extreme temperature, rocks are easily weathered.

(iv) Vegetation cover – At times, plants grow in the cracks existing in a rock. With time, the roots of these plants start penetrating in the cracks and making them wider. As a result, cracks disintegrate into smaller pieces and help in soil formation.

(v) Time – Time gives maturity to the soil. Although soil is a renewable resource, yet it takes thousands of years to develop a very thin layer of soil on the earth’s surface.

2. What is meant by land use pattern? Why is it important to study the land use pattern? List the factors influencing the utilization of land.

Answer: Land is used for various purposes, such as cultivation of crops, building of houses, Construction of roads and railways, grazing of animals, etc. This is commonly known as the land use pattern.

The study of land use patterns is important for the economic planning of a nation. It helps to assess Shortcomings in land utilization.

The factors influencing the utilization of land are climate, relief features, water bodies, and soil.

3. What are Multipurpose River Valley Projects? Name any two such projects. List the main objectives of a multipurpose river valley project.

Answer: The multipurpose river valley project is a river project in which a dam is constructed across the river for storing water.

Two projects are the Damodar River Valley project and the Hirakund Dam.

The main objectives of a multipurpose river Valley project are:

• Irrigation
• Afforestation
• flood control
• Generation of hydroelectricity

4. Suggest any five steps to conserve soil.

Answer: Soil conversation means prevention of soil from being eroded. Various methods for soil conservation are:

• Planting more and more trees
• Raising fodder crops.
• Restricting the free movement of animals in the fields.
• Checking the reckless Cutting of trees.
• Adopting Scientific agricultural practices like rotation of crops, Strip cropping, etc.

5. Suggest any five methods for the conservation of water.

Answer: Five methods for the conservation of water is:

• 1)Water harvesting is one of the methods of saving surface runoff.
• 2)The rainwater can be impounded by making dams across the rivers.
• 3)The demand for water for industries can be met by recycled water.
• 4)Water can be saved by adopting modern methods of irrigation.
• 5)Water can be conserved by installing water fixtures, such as sensor taps in public places.