Class 7 Science chapters help the students create a solid base for the science subject. The syllabus introduces the students to many new concepts, and they learn about the secondary education format and exam patterns.
Chapter 9 of Class 7 Science syllabus is about soil. The students learn about soil types, moisture in the soil, properties in the soil, etc. There are practise questions at the end of the chapter to help students gauge their understanding of the concepts covered in the chapter. If students are looking for accurate answers to these questions, they can refer to NCERT Solution Class 7 Science Chapter 9.
Extramarks brings the NCERT Solutions to the Class 7 students to encourage them further to study more throughout their learning process. Class 7 Science Chapter 9 Solutions teach the students to learn, analyse, and write answers. The students can finish the syllabus on time with the help of NCERT Solutions and secure more marks in the examination with excellent performance.
NCERT Solutions for Class 7 Science Chapter 9
Access NCERT Solutions for Class 7 Science Chapter No. 9 – Soil
NCERT Solutions for Class 7 Science Chapter 9 Soil help the students solve even the most difficult or tricky questions easily. The subject-matter experts prepare the NCERT Solutions based on the CBSE syllabus and guidelines. The solutions simplify the study process with accurate answers followed by examples. The students need to solve the Class 7 Science Chapter 9 question answers regularly to continue the learning process and remember the facts. It encourages and motivates the students to perform well in the examination. The solutions are easily accessible on the Extramarks website or app.
Chapter 9 – Soil
The chapter helps students understand every aspect of soil effortlessly. The topics and subtopics included in Chapter 9- Soil are given below:
- 9.0. Soil
- 9.1. Soil Teeming with Life
- 9.2. Soil Profile
- 9.3. Soil Types
- 9.4. Properties of Soil
- 9.5. Moisture of Soil
- 9.6. Absorptions of Water by Soil
- 9.7. Soil and Crops
9.1. Soil Teeming with Life
Soil is one of the most widely available yet precious natural resources. It comprises numerous species that form a dynamic and complex ecosystem. Both plants and animals play a key role in keeping the soil fertile. For instance, the roots of the plants go inside the soil and help in binding it. The excreta of animals has nutrients for improving the structure of the soil.
Apart from animal inhabitants like slugs, snails, rodents, spiders, insects, mites, and earthworms, there are numerous microscopic bacterial colonies. Some of these are helpful, and some are not.
The two most harmful elements to contaminate soil are plastic and polythene. These two are also responsible for killing burrowing organisms and affecting the entire ecosystem. It is essential to ban plastics and their by-products immediately to save the earth. Other substances such as chemicals, waste products, and pesticides are harmful to the soil.
9.2. Soil Profile
Soil comprises different layers. The students can perform a small experiment to explore the different layers of soil. The presence of the rotting dead bodies is known as humus. Soil is formed by the breakdown of rocks by water, wind and climate. This process has been termed 'weathering'.
The vertical sections of different soil layers are known as the soil profile. Each layer varies in colour, texture, depth, and chemical composition. These layers are known as horizons.
Usually, the uppermost horizon layers are dark in colour due to the presence of humus and minerals. The humus keeps the soil fertile and supplies nutrients to the plants. This layer has pores that can absorb water. It provides shelter to several living organisms like worms, rodents, beetles and so on. This layer is known as the topsoil or A-horizon.
The middle layer is also known as B-horizon. The lower layer of the soil possesses more nutrients and less humus. The layer is more compact and concrete.
The third layer is the C-horizon which consists of small lumps of rocks with cracks and crevices. Beneath this layer lies the bedrock. The hardness of this layer prevents digging with a spade.
9.3. Soil Types
Weathering of rocks is responsible for producing little parts of various materials that comprise sand and clay. The amount of sand and clay depends on the rock from which these particles have originated. It is known as the parent rock. The blend of rock particles and rock is known as soil. Soil can be classified based on the presence of particles of different sizes.
Let us have a look at the soil types:
- Sandy Soil: When the soil has a large proportion of bigger particles, it is known as sandy soil. It contains very little humus and is found in desert areas.
- Clayey Soil: When the soil holds more fine particles, it is known as clayey soil. It is heavy because it can hold more water because of tightly packed particles.
- Loamy Soil: When the soil holds an equal amount of fine and larger particles of silt, sand, clay is known as loamy soil.
The presence of particles in the soil has an impact on the properties. Sometimes, the particles are so large that they can't fit together. Air fills the large spaces between the particles. Water can drain through these spaces at ease. In the case of clayey soil, the smooth elements absorb the water, so it is a heavy soil type. On the other hand, the best kind of soil is loamy. It is a combination of clay, sand, and silt. It is the best soil type to grow plants as it can be ploughed easily.
9.4. Properties of Soil
- Soil Texture: It depends on the quantity of silt, particle size and clay size apart from the organic elements present in the soil.
- Soil Structure: It reflects how the clay particles, silt, and sand have come together.
- Soil Porosity: It refers to the number of pores present in the soil.
- Soil Colour: It can range from black to red to white. Sometimes, the colour of the soil can be blue. The colour indicates the abundance of an element.
9.5. Moisture in Soil
The amount of water a soil type can hold is known as the moisture in the soil. The moisture has a profound impact on the ecological process. Many predictions for farming, erosion prevention, drought prediction, and flood control are based on soil moisture.
9.6. Absorption of Water by Soil
Clayey soil can hold water but is poor in aeration. Sandy soil cannot hold water between the rock particles. Therefore, it is not suitable for plant growth. Loamy soil has the best water absorption capacity. It also provides excellent aeration.
9.7. Soil and Crops
India has different kinds of soils in different parts of the country. Factors like sunlight, rainfall, humidity, temperature and wind stimulate soil type. The elements and climatic reasons determine the growth of crops and vegetation in a region. Loamy and clayey soils are ideal for growing cereals as these two can retain water. Sandy soil is not suitable for agricultural activities in its entirety.
Key Features of NCERT Solutions for Class 7 Science Chapter 9
The key features of NCERT Solutions are:
- The solutions follow the CBSE syllabus and guidelines.
- Experienced faculty prepare the subject-wise solutions.
- The solutions cover all the answers from the textbook chapters.
Q.1 Tick the most suitable answer.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
In addition to the rock particles, the soil contains (iii) minerals, organic matter, air and water.
Q.2 Tick the most suitable answer.
The water holding capacity is the highest in
(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam
The water holding capacity is the highest in (ii) clayey soil.
Q.3 Match the items in Column I with those in Column II:
|Column I||Column II|
|(i) A home for living organisms||(a) Large particles|
|(ii) Upper layer of the soil||(b) All kinds of soil|
|(iii) Sandy soil||(c) Dark in colour|
|(iv) Middle layer of the soil||(d) Small particles and packed tight|
|(v) Clayey soil||(e) Lesser amount of humus|
The correctly matched contents of Column I and Column II are as follows:
|Column I||Column II|
|(i) A home for living organisms||(b) All kinds of soil|
|(ii) Upper layer of the soil||(c) Dark in colour|
|(iii) Sandy soil||(a) Large particles|
|(iv) Middle layer of the soil||(e) Lesser amount of humus|
|(v) Clayey soil||(d) Small particles and packed tight|
Q.4 Explain how soil is formed.
Soil is formed by the process of weathering. In this process, rocks are broken into smaller particles by the action of wind, water and various other climatic factors. The slow and continuous action of these factors converts massive rocks into fine particles of soil over a period of millions of years.
Q.5 How is clayey soil useful for crops?
Clayey soil has maximum water holding capacity due to which it retains water for absorption by the plants for longer period of time. Also, clayey soil is rich in humus that provides nutrients to the plants for their growth. Thus, clayey soil is very useful for the crops.
Q.6 List the differences between clayey soil and sandy soil.
The differences between clayey soil and sandy soil are as follows:
|S. no.||Clayey soil||Sandy soil|
|1.||Soil particles are very fine.||Soil particles are very large.|
|2.||Soil particles are compactly bound to each other.||Soil particles are not bound to each other.|
|3.||Soil has high water holding capacity.||Soil has poor water holding capacity.|
|4.||Soil supports the growth of most of the crops.||Soil supports the growth of only few types of crops.|
Q.7 Sketch the cross section of soil and label the various layers.
Following is the well-labelled sketch of the cross-section of soil and its various layers:
Q.8 Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
The percolation rate is given by the following expression:
Percolation rate = amount of water (mL)/time taken(min)
Therefore, Percolation rate = 200 mL/40min
= 5 mL/min
Q.9 Explain how soil pollution and soil erosion could be prevented.
Ways of preventing soil pollution are as follows:
1. Minimising the use of pesticides and fertilisers
2. Banning the use of polythene
3. Treating chemicals and other waste products of industries before releasing them into soil or water
4. Abandoning the practice of defecation in open
Ways of preventing soil erosion are as follows:
1. Planting of trees at large scale
2. Putting check on deforestation
3. Protecting and expanding forest covers
Q.10 Solve the following crossword puzzle with the clues given:
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
The correctly solved crossword puzzle is as follows:
FAQs (Frequently Asked Questions)
You will find the subject-wise NCERT Solutions for Class 7 on Extramarks on the official website or app.
Science Chapter 9 of the Class 7 syllabus includes soil teeming with life, soil profile, soil types, soil properties, soil moisture, absorptions of water by soil, soil and crops, etc.