CBSE Class 7 Science Exemplar Chapter 16: Water - A Precious Resource NCERT Solutions
This chapter, Water: A Precious Resource, for CBSE Class 7 Science, explores the vital importance of water and its conservation. The NCERT Solutions guide students through understanding the scarcity of usable freshwater, recognizing signs of water shortage, and differentiating the various states of water. Key concepts like the water table are explained, alongside practical methods for water conservation such as rainwater harvesting and drip irrigation. These solutions offer clear, step-by-step explanations designed to enhance comprehension of water's significance and the necessity of its judicious use. They serve as an excellent resource for students aiming to excel in their exams and develop a strong sense of environmental stewardship.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 7 |
| Subject | Science Exemplar |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 16 |
Chapter summary
Chapter 16, "Water: A Precious Resource," focuses on the significance of water as a vital natural resource. The NCERT Solutions address key concepts like water scarcity indicators, the low percentage of available freshwater, and the different physical states of water. It also explains the concept of the water table and explores various water conservation techniques. This chapter's solutions are designed to build a foundational understanding of water's importance and the need for its judicious use.
Learning outcomes
- Identify situations indicating water shortage.
- Understand the limited availability of freshwater on Earth.
- Differentiate between solid, liquid, and gaseous forms of water.
- Define and locate the water table.
- Recognize methods for economical water usage.
Topics covered
Paper topics
- Water Scarcity
- Availability of Freshwater
- States of Water (Solid, Liquid, Gas)
- Water Table
- Groundwater
- Water Conservation
- Rainwater Harvesting
- Drip Irrigation
Important topics
- Availability of Freshwater
- Water Table
- Water Conservation Methods
- Signs of Water Shortage
PDF preview
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Questions and Solutions
Multiple Choice Questions
(a) Taps running dry.
(b) Long queues for getting water.
(c) Marches and protests for demand of water.
(d) A family gets three buckets of water per person per day.
Explanation: The United Nations recommends a minimum of 50 liters of water per person per day for adequate living. If a family receives three buckets of water daily, this amount is generally considered sufficient and does not represent a situation of water shortage.
(a) <math>0.006\%</math>.
(b) 0.06%.
(c) <math>0.6\%</math>.
<math>(d) 6\%</math>.
Explanation: A significant portion of Earth's water, about 97.4%, is found in seas and oceans, which is saline. Another 2% is frozen in glaciers and polar ice caps. This leaves only a small fraction, approximately 0.6%, as freshwater in liquid form. Out of this 0.6%, a large part (0.59%) is groundwater, and only about 0.01% is available as surface freshwater, making it extremely scarce for direct use.
Exercise Questions
Choose the correct combination from the options below.
(i) Snow
(ii) Lake water
(iii) River water
(iv) Water vapour
(v) Ice
Options:
(a) (i), (iv) and (v)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iv) only
Explanation: Water exists in three states: solid, liquid, and gas. Snow and ice are the solid forms of water. Water vapour is the gaseous form of water. Lake water and river water are examples of the liquid form of water.
Options:
(a) water level.
(b) water table.
(c) ground water.
(d) water limit.
Explanation: The water table represents the uppermost level of the saturated zone in the ground, where all the pores and cracks in the soil and rocks are filled with water. The water found below this level is known as groundwater.
(a) Construction of bawris
(b) Rainwater harvesting
(c) Drip irrigation
(d) Infiltration
Explanation: Rainwater harvesting involves collecting and storing rainwater for later use, thus conserving water. Drip irrigation is a method that delivers water directly to the roots of plants in small quantities, significantly reducing water wastage through evaporation and runoff. While bawris (stepwells) can help store water and infiltration helps recharge groundwater, rainwater harvesting and drip irrigation are direct methods of economical usage and conservation.
Common mistakes
- Confusing solid/gaseous water forms with liquid water.
- Misunderstanding the definition of the water table.
- Not recognizing all listed methods as water-saving techniques.
Revision tips
- Review the percentages of water availability on Earth.
- Memorize the different states of water and their examples.
- Understand the practical implications of water scarcity.
- Focus on the methods of water conservation discussed.
Practice MCQs
Q1. Which of the following scenarios best indicates a severe water shortage?
Explanation: While the other options are clear signs of water shortage, receiving three buckets of water per person per day is considered adequate by UN standards and thus does not indicate a shortage.
Q2. What approximate percentage of Earth's water is readily available as liquid freshwater for human use?
Explanation: Only a very small fraction, approximately 0.006%, of Earth's total water is available as surface freshwater, with most being saline or frozen.
Q3. Which of the following are NOT considered liquid forms of water?
Explanation: Snow and ice are solid states of water, while water vapour is the gaseous state. Lake water and river water are liquid forms.
Q4. The upper boundary of the saturated soil layer, where spaces between soil particles and rock gaps are filled with water, is known as the:
Explanation: This upper limit is precisely defined as the water table. Water found below this level is termed groundwater.
Q5. Which of the following practices is most effective for using water economically?
Explanation: Drip irrigation delivers water directly to plant roots, minimizing evaporation and wastage, making it a highly economical method.
Frequently asked questions
What does Chapter 16 of CBSE Class 7 Science Exemplar focus on?
Chapter 16, 'Water: A Precious Resource,' focuses on understanding water scarcity, the limited availability of usable freshwater, the different states of water, the concept of the water table, and methods for conserving water.
How do these NCERT Solutions help students?
These solutions provide clear, rewritten explanations for each question, helping students understand the concepts related to water resources and conservation, which is crucial for their exams.
What are the main indicators of water shortage mentioned in the solutions?
The solutions indicate that taps running dry, long queues for water, and public protests for water are signs of water shortage.
What is the significance of the water table?
The water table is the upper level of the layer of soil and rock that is saturated with water. Understanding it is key to comprehending groundwater resources.
What are some economical ways to use water discussed in the solutions?
The solutions highlight practices like rainwater harvesting and drip irrigation as effective methods for using water economically and conserving this precious resource.
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