Water – A Precious Resource Class 7 Science Notes and Questions Answers
Introduction: Water is one of the most essential natural resources for life on Earth. Without water, survival is not possible. This chapter from Class 7 Science, “Water – A Precious Resource”, explains the importance of water, its distribution, shortage, and the need to conserve it. Below, you will find simplified chapter notes followed by important questions and answers including multiple-choice questions, very short answers, short answers, and long answers. This study material is designed for easy exam preparation and better understanding.
📘 Notes of Water – A Precious Resource (Class 7 Science)
1. Importance of Water
Water is essential for drinking, agriculture, industry, electricity generation, sanitation, and maintaining the balance of the ecosystem. All living beings depend on it for survival.
2. Distribution of Water on Earth
About 71% of the Earth’s surface is covered with water, but only a small fraction is available for human use. Out of the total water:
- 97% is salt water in oceans and seas.
- Only 3% is fresh water, out of which a major part is locked in glaciers and ice caps.
- Less than 1% of water is available for human use in rivers, lakes, groundwater, and atmosphere.
3. Groundwater as a Resource
Groundwater is the main source of water for agriculture, drinking, and industries. It is stored in aquifers below the Earth's surface. Overuse of groundwater leads to depletion, creating scarcity in many regions.
4. Causes of Water Shortage
- Overpopulation and increasing demand.
- Excessive use in agriculture and industries.
- Deforestation and loss of catchment areas.
- Pollution of rivers and lakes.
- Climate change and irregular rainfall.
5. Water Management
Conservation and proper management of water is necessary to ensure sustainable use. Some measures include:
- Rainwater harvesting – collecting and storing rainwater for future use.
- Drip irrigation – efficient method of watering plants drop by drop.
- Reuse and recycling of water in industries and households.
- Awareness programs to prevent water wastage.
6. Distribution of Water in India
India faces uneven distribution of water resources. Some states receive abundant rainfall, while others face droughts. Seasonal dependency on monsoon makes the situation more challenging.
7. Role of Each Individual
Every person can contribute to water conservation by using water carefully, fixing leakages, turning off taps, reusing water where possible, and spreading awareness.
📝 Questions and Answers of Water – A Precious Resource
Multiple Choice Questions (MCQs)
- What percentage of Earth’s surface is covered with water?
a) 51%
b) 61%
c) 71%
d) 81%
Answer: c) 71% - Which of the following is the largest source of freshwater?
a) Rivers
b) Glaciers and ice caps
c) Groundwater
d) Lakes
Answer: b) Glaciers and ice caps - The underground layer storing water is called:
a) Aquifer
b) Reservoir
c) Dam
d) Well
Answer: a) Aquifer - Which method of irrigation saves the most water?
a) Flood irrigation
b) Drip irrigation
c) Sprinkler irrigation
d) Canal irrigation
Answer: b) Drip irrigation - Which one is NOT a cause of water shortage?
a) Deforestation
b) Overpopulation
c) Abundant rainfall
d) Overuse in industries
Answer: c) Abundant rainfall - Which of the following is a water conservation practice?
a) Leaving taps open
b) Rainwater harvesting
c) Wasting water in industries
d) Over-irrigation
Answer: b) Rainwater harvesting - Groundwater depletion is mainly caused by:
a) Planting trees
b) Heavy rainfall
c) Excessive pumping of water
d) Use of drip irrigation
Answer: c) Excessive pumping of water
Very Short Answer Questions
- What fraction of Earth’s water is fresh water?
Answer: About 3%. - Name two methods of water conservation.
Answer: Rainwater harvesting and drip irrigation. - What is groundwater?
Answer: Water stored underground in soil and rocks, called aquifers. - Which is the main source of drinking water?
Answer: Groundwater. - Name the process of collecting rainwater.
Answer: Rainwater harvesting. - What percentage of water is saline?
Answer: About 97%. - Give one cause of water scarcity.
Answer: Overpopulation.
Short Answer Questions
- Why is water called a precious resource?
Answer: Because only a small fraction of water is available for use, and it is essential for life, agriculture, industry, and maintaining the ecosystem. - How does deforestation affect water availability?
Answer: Deforestation reduces rainfall, increases runoff, decreases groundwater recharge, and causes drought-like conditions. - What are aquifers?
Answer: Aquifers are underground layers of porous rocks or soil that store water, which can be extracted through wells and tube wells. - What is drip irrigation and why is it useful?
Answer: Drip irrigation delivers water directly to the base of plants drop by drop, reducing wastage and conserving water. - Why is rainwater harvesting important in India?
Answer: Because India depends heavily on monsoon rains, harvesting ensures water storage for dry seasons and reduces groundwater depletion. - Explain why some regions face drought despite heavy rainfall in India.
Answer: Uneven distribution of rainfall causes floods in some areas and drought in others. - How can students help in water conservation?
Answer: By closing taps properly, reusing water for gardening, spreading awareness, and participating in school campaigns.
Long Answer Questions
- Explain the distribution of water on Earth.
Answer: About 71% of Earth is covered with water. Out of this, 97% is salty ocean water. Only 3% is fresh water, but most of it is in glaciers and ice caps. Less than 1% is available in rivers, lakes, and groundwater for human use. This makes water a precious resource that must be conserved. - Discuss the causes of water shortage.
Answer: Water shortage occurs due to overpopulation, deforestation, pollution of water bodies, climate change, excessive use in agriculture and industries, and over-extraction of groundwater. These activities reduce the availability of fresh water for people, plants, and animals. - How can water be conserved at home and community level?
Answer: At home, water can be conserved by fixing leakages, using buckets instead of showers, reusing water for gardening, and turning off taps. At community level, rainwater harvesting, awareness campaigns, and building check dams can help conserve water. - Write a note on groundwater depletion.
Answer: Groundwater depletion is the excessive use of water stored underground. It happens due to over-irrigation, pumping of water for industries and cities, and lack of recharge due to deforestation and paved surfaces. It leads to lowering of water tables, drying up of wells, and scarcity of drinking water. - Describe any three methods of water management.
Answer: (i) Rainwater harvesting: Collecting rainwater from rooftops and storing it in tanks or recharging wells. (ii) Drip irrigation: Providing water directly to plants in a controlled way to reduce wastage. (iii) Reuse and recycling: Treating used water in industries and households for non-drinking purposes. - Why is it important to involve every individual in water conservation?
Answer: Because water scarcity affects all. If each person saves water in daily life, the cumulative effect will be large. Individual efforts like turning off taps, avoiding wastage, and supporting rainwater harvesting can reduce water shortage significantly. - What steps should India take to ensure sustainable use of water?
Answer: India should promote efficient irrigation methods, construct check dams, enforce pollution control, invest in rainwater harvesting, recycle industrial water, and spread awareness among citizens. Long-term policies are needed to manage both demand and supply of water.
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