Exercises: Water: A Precious Resource | Class 7 Oxford Science: Chapter Notes, Worksheets & Tests PDF Download

Objective Type Questions 

Water is used in the industries for generating electricity.
Water is used in hydroelectric power plants to generate electricity.

Q.2. ______________(Aquifer/Dams) are built on rivers to regulate the flow of water and distribute it more evenly throughout the year. 

Dams are built on rivers to regulate the flow of water and distribute it more evenly throughout the year.
Dams are built to impound water and regulate its flow for various purposes such as irrigation, hydroelectric power generation, and flood control.

Q.3. _______________(Punjab/Tamil Nadu) receives over half of its rain from October to November, 

Tamil Nadu receives over half of its rain from October to November.
Tamil Nadu receives most of its rainfall during the northeast monsoon season that occurs from October to December.

Q.4. _______________ (Sea/River) water is not fit for domestic and agricultural use.

Sea water is not fit for domestic and agricultural use.
Sea water has a high salt content and is not suitable for domestic or agricultural use without desalination.

Q.5. __________ (Gangetic/Coastal) plains can get contaminated by saltwater inflow caused by the over pumping of groundwater. 

Coastal plains can get contaminated by saltwater inflow caused by the over-pumping of groundwater.
Over-pumping of groundwater can cause saltwater intrusion into coastal aquifers, leading to contamination of freshwater resources.

Q.6. Rainwater harvesting systems help in _____________(scarcity/conservation) of water.

Rainwater harvesting systems help in conservation of water.
Rainwater harvesting systems collect and store rainwater for later use, reducing the demand on freshwater resources and promoting water conservation.

B. Choose the correct option.

Very Short Answer Type Questions 

Cooling in power plants, manufacturing processes in factories

Q.2. Domestic usage of water __________ ___________

Drinking, washing clothes

Q.3. Source of surface water __________ ___________

Rivers, lakes, ponds, reservoirs

Q.4. Rivers that originate in the Himalayas__________ ___________

Ganga, Brahmaputra

Q.5. Effluents that pollute water __________ ___________

Chemicals, sewage, fertilizers

Short Answer Type Questions 

Surface water refers to water sources that are visible on the surface of the earth, such as rivers, lakes, and oceans. Groundwater, on the other hand, refers to water that is present beneath the earth's surface, in soil and rock formations.

Q.2. What is water table? How is a natural spring formed? 

The water table is the level at which the underground water is found. A natural spring is formed when the water table intersects the ground surface, causing water to flow out of the ground.

Q.3. Why monsoons are important for our country? 

Monsoons are important for our country because they bring much-needed rainfall, which is necessary for agriculture and replenishing water sources. They also help regulate the temperature and climate of the region.

Q.4. How does deforestation contribute to scarcity of water? 

Deforestation contributes to scarcity of water as trees play a crucial role in the water cycle. They help regulate the flow of water by absorbing it through their roots and releasing it back into the atmosphere through a process called transpiration. When trees are cut down, this process is disrupted, leading to a decrease in water availability.

Q.5. How does scarcity of water affect plants? 

Scarcity of water affects plants by causing them to wilt, dry up, and eventually die. This can have a ripple effect on the ecosystem, as plants are an important food source for animals, and also help regulate the climate and water cycle.

Long answer type questions 

Water is a unique substance that exists in all three states, i.e., solid, liquid, and gas, in our natural environment. These states are found in various forms, such as:

(a) Solid state: In the solid state, water exists as ice, snow, and hail. It is found in glaciers, ice caps, and snow-capped mountains. In polar regions, large masses of ice called icebergs float in the oceans.

(b) Liquid state: In the liquid state, water exists in rivers, lakes, oceans, and underground water bodies. It is the most commonly found state of water on our planet.

(c) Gas state: In the gas state, water exists as water vapor, which is present in the air we breathe. It is also present in the form of clouds in the atmosphere.

Q.2. Discuss the various factors that have contributed to the depletion of water table. 

The depletion of the water table is a serious issue that is caused by various factors, such as:

(a) Overuse of groundwater: The excessive use of groundwater for agriculture, industries, and domestic purposes leads to a decline in the water table.

(b) Climate change: Climate change has a significant impact on the water cycle, which affects the availability of water in different regions.

(c) Deforestation: The removal of trees and vegetation leads to a decrease in the amount of water that is absorbed by the soil, resulting in lower groundwater levels.

(d) Pollution: The contamination of groundwater sources due to industrial waste, chemicals, and sewage leads to a decrease in the quality of water and makes it unfit for consumption.

Q.3. Explain the various practices that can be adopted to conserve water.

Water conservation is critical for the sustainable use of this precious resource. Various practices can be adopted to conserve water, such as:

(a) Rainwater harvesting: Rainwater harvesting is a process of collecting and storing rainwater for future use. This practice helps to recharge groundwater and reduce the dependence on surface water sources.

(b) Efficient use of water: Efficient use of water can be achieved by the use of low-flow fixtures, drip irrigation systems, and water-efficient appliances. This practice can reduce the water demand in households and industries.

(c) Water reuse: The reuse of wastewater for non-potable purposes such as irrigation, washing, and cleaning can reduce the demand for freshwater sources.

(d) Planting trees: Planting trees and vegetation helps to increase the water-holding capacity of the soil, which leads to the recharge of groundwater sources.