CBSE Class 7 Science Chapter 16: Water: A Precious Resource NCERT Solutions
This chapter delves into the critical topic of water as a precious resource, essential for all life on Earth. The NCERT Solutions for Class 7 Science, Chapter 16, provide clear explanations and answers to key questions about water. Students will learn about the different forms of water, the water cycle, the concept of groundwater, and the factors contributing to its depletion. The solutions also address the importance of water conservation and methods to minimize water usage, especially in gardening. Understanding these concepts is vital for appreciating the scarcity of freshwater and the need for responsible water management. These solutions are designed to help students grasp the fundamental principles of water resources and prepare effectively for their exams by offering detailed explanations and accurate answers to all exercise questions.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 7 |
| Subject | Science |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 16: Water: A Precious Resource |
Chapter summary
Chapter 16, 'Water: A Precious Resource,' focuses on understanding the significance of water, its various forms, and sources. The NCERT Solutions cover topics like groundwater, its recharge, and depletion factors such as increasing population and deforestation. It also touches upon water conservation techniques and the continuous nature of the Earth's water. The exercises aim to reinforce concepts related to the water cycle and responsible water usage.
Learning outcomes
- Understand the importance of water as a precious resource.
- Identify the different forms and sources of water.
- Explain the process of groundwater recharge and factors affecting the water table.
- Recognize the causes of water scarcity and depletion.
- Discuss methods for water conservation and minimizing water usage.
- Differentiate between true and false statements regarding water resources.
Topics covered
Paper topics
- Forms of Water
- Sources of Water
- Groundwater
- Water Table
- Groundwater Recharge
- Infiltration
- Water Depletion
- Causes of Water Scarcity
- Water Conservation
- Irrigation Methods
- Population Growth Impact
- Deforestation Impact
Important topics
- Groundwater and its Recharge
- Factors Responsible for Water Table Depletion
- Water Conservation Methods
- Rain as the Ultimate Source of Water
- Understanding Water Scarcity
PDF preview
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Questions and Solutions
Question 1
(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world.
(b) Water shortage is a problem faced only by people living in rural areas.
(c) Water from rivers is the only source for irrigation in the fields.
(d) Rain is the ultimate source of water.
(a) T - Groundwater holds a significantly larger volume of freshwater compared to the surface water found in rivers and lakes globally.
(b) F - Water shortage is a widespread issue affecting both rural and urban populations due to increasing demand and uneven distribution.
(c) F - While rivers are important sources, irrigation also relies on groundwater, canals, and other methods.
(d) T - Rain is the primary source that replenishes all other water bodies, including rivers, lakes, and groundwater, making it the ultimate source.
Question 2
Groundwater gets recharged through a natural process called infiltration. When it rains, or when water from sources like rivers and ponds flows, some of this water seeps down through the soil layers. This water gradually penetrates deeper, filling up the empty spaces and cracks in the rocks and soil beneath the surface. This continuous seepage replenishes the underground water reserves, effectively recharging the groundwater.
Question 3
Having ten tube-wells for only fifty houses suggests a high rate of groundwater extraction. If the rate at which water is pumped out exceeds the rate at which it is replenished through natural processes like infiltration, the water table will gradually decrease over the long term. This excessive withdrawal can lead to a significant drop in the water level, potentially causing water scarcity for the community.
Question 4
To minimize water usage in maintaining a garden, several strategies can be employed. Firstly, using water-efficient irrigation methods such as drip irrigation, which delivers water directly to the plant roots, or sprinklers, which distribute water over the area, can significantly reduce wastage. Secondly, watering should ideally be done during cooler parts of the day, like early morning or late evening, to minimize water loss through evaporation. Mulching around plants can also help retain soil moisture.
Question 5
Several factors contribute to the depletion of the water table:
- Increasing Demand: The rising population leads to a greater demand for water for domestic use, agriculture, and industries, resulting in more water being extracted from underground sources.
- Deforestation: The removal of forests reduces the natural surface area that can absorb rainwater and facilitate infiltration. Trees play a crucial role in the water cycle, and their absence disrupts the natural process of groundwater recharging.
- Urbanization and Land Use Changes: Paved surfaces in urban areas reduce the amount of rainwater that can seep into the ground, hindering recharge.
The imbalance created by increased demand and reduced recharging capacity is the primary reason for the depletion of the water table.
Question 6
(a) People obtain groundwater through_____ and _____.
(b) Three forms of water are _____, ____ and _____.
(c) The water bearing layer of the earth is _____.
(d) The process of water seepage into the ground is called _____.
(a) People obtain groundwater through wells and tubewells.
(b) Three forms of water are solid, liquid and gas.
(c) The water bearing layer of the earth is water table.
(d) The process of water seepage into the ground is called infiltration.
Question 7
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
The correct option is (iii) Heavy rainfall. Heavy rainfall generally increases the availability of water and helps in replenishing water sources, thus it does not contribute to water shortage.
Question 8
(i) in the lakes and rivers of the world remains constant.
(ii) under the ground remains constant.
(iii) in the seas and oceans of the world remains constant.
(iv) of the world remains constant.
The correct option is (iv) of the world remains constant. While water moves between different reservoirs (oceans, atmosphere, land) through the water cycle, the total amount of water on Earth remains relatively constant over long periods.
Common mistakes
- Confusing groundwater with surface water sources.
- Underestimating the impact of human activities on water table depletion.
- Assuming water is an inexhaustible resource.
- Not considering rainfall as the ultimate source of all water.
Revision tips
- Focus on understanding the 'why' behind each true/false statement in Question 1.
- Draw a simple diagram to visualize the groundwater recharge process explained in Question 2.
- Relate the concepts of population growth and deforestation to water table depletion (Question 5) with real-world examples.
- Practice filling in the blanks in Question 6 to recall key terms and definitions.
- Think critically about why heavy rainfall (Question 7) doesn't cause water shortage.
Practice MCQs
Q1. Which of the following is the ultimate source of water on Earth?
Explanation: Rain is considered the ultimate source of water because it replenishes rivers, lakes, and groundwater, forming the basis of the water cycle.
Q2. What is the process of water seeping into the ground called?
Explanation: Infiltration is the term used to describe the movement of surface water through the soil and into the ground, which recharges groundwater.
Q3. Which factor is NOT responsible for water shortage?
Explanation: Heavy rainfall generally increases the availability of water and helps in recharging water sources, thus it does not cause water shortage.
Q4. What is the water-bearing layer of the Earth called?
Explanation: The water table represents the upper level of the saturated zone in the ground, indicating the level below which the soil is filled with water.
Q5. Which of these is a method to minimize water use in gardening?
Explanation: Sprinklers and drip irrigation systems are efficient methods that deliver water directly to plant roots, reducing wastage through evaporation and runoff.
Frequently asked questions
What is the main focus of CBSE Class 7 Science Chapter 16?
Chapter 16, 'Water: A Precious Resource,' focuses on understanding the importance of water, its sources, groundwater, the water cycle, and the critical need for water conservation.
How is groundwater recharged according to the NCERT Solutions?
Groundwater is recharged through the process of infiltration, where rainwater and water from rivers and ponds seep through the soil, filling empty spaces and cracks deep below the ground.
What are the primary reasons for the depletion of the water table?
The depletion of the water table is mainly due to increased demand for water from a growing population and reduced natural groundwater recharging, often exacerbated by deforestation.
Are water shortages only a problem in rural areas?
No, water shortage is a problem faced by people in both rural and urban areas due to various factors like increasing demand, mismanagement, and unequal distribution.
How can water usage be minimized in a garden?
Water usage in a garden can be minimized by using efficient methods like drip irrigation and sprinklers, and by watering plants at times that reduce evaporation loss.
Why is rain considered the ultimate source of water?
Rain is the ultimate source of water because it is the primary way that freshwater is replenished on Earth, feeding rivers, lakes, and recharging groundwater reserves.
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