Water Resources - 2 Class 4 Worksheet SST

Q1: Fill in the Blanks.

(i) Water covers about __________% of the Earth's surface.
Ans: 70%
Water covers about 70% of the Earth's surface. The vast majority of Earth's surface is covered by water, primarily in the form of oceans, seas, and other bodies of water.

(ii) The process of water turning into vapor is called __________.
Ans: Evaporation
The process of water turning into vapor is called evaporation. Evaporation is the phase transition from a liquid (water) to a gas (water vapor) when heat energy is applied. It is a fundamental part of the Earth's water cycle.

(iii) The largest source of freshwater on Earth is __________.
Ans: Icecaps and glaciers
The largest source of freshwater on Earth is icecaps and glaciers. Icecaps and glaciers store a significant portion of Earth's freshwater in the form of ice. When this ice melts, it contributes to the planet's freshwater resources.

(iv) __________ is the natural cycle of water movement between the Earth's surface and the atmosphere.
Ans: Water cycle
The water cycle is the natural cycle of water movement between the Earth's surface and the atmosphere. It involves processes such as evaporation, condensation, precipitation, and runoff, which continuously recycle water on Earth.

(v) __________ is the term for water that falls from the atmosphere to the ground in the form of rain, snow, sleet, or hail.
Ans: Precipitation
Precipitation is the term for water that falls from the atmosphere to the ground in the form of rain, snow, sleet, or hail. Precipitation is a key component of the water cycle and is vital for maintaining freshwater resources.

(vi) A large body of water surrounded by land is called a __________.
Ans: Lake
A large body of water surrounded by land is called a lake. Lakes are formed in various ways, including through geological processes, and they vary in size and characteristics.

(vii) __________ is the process of removing salt and other impurities from seawater to make it suitable for drinking and irrigation.
Ans: Desalination
Desalination is the process of removing salt and other impurities from seawater to make it suitable for drinking and irrigation. This process is essential in regions with limited access to freshwater sources.

(viii) The three states of water are liquid, __________, and gas.
Ans: Solid
The three states of water are liquid, solid, and gas. In the solid state, water is in the form of ice; in the liquid state, it is the familiar form of liquid water, and in the gas state, it exists as water vapor in the atmosphere.

(ix) __________ is a human-made water storage area usually formed by building a dam across a river.
Ans: Reservoir
Reservoir is a human-made water storage area usually formed by building a dam across a river. Reservoirs are created for various purposes, including water supply, irrigation, hydroelectric power generation, and recreation.

(x) The underground layer of rock or sediment that holds water is called an __________.
Ans: Aquifer
The underground layer of rock or sediment that holds water is called an aquifer. Aquifers are crucial sources of groundwater, and they supply water to wells and springs, as well as serving as a vital component of the Earth's freshwater resources.

Q2: Multiple Choice Questions (MCQs).

(i) What percentage of Earth's water is freshwater?
(a) 25%
(b) 50%
(c) 75%
(d) 90%
Ans: (d)
While about 70% of the Earth's surface is covered by water, only around 2.5-3% of that water is freshwater. The majority of freshwater is locked in icecaps, glaciers, and underground aquifers.

(ii) Which of the following is a natural source of freshwater?
(a) Ocean
(b) Lake
(c) Saltwater river
(d) Saltwater well
Ans: (b)
Lakes, rivers, and groundwater are natural sources of freshwater. Oceans contain saltwater.

(iii) What is the main purpose of a dam?
(a) Generating electricity
(b) Providing a place for fishing
(c) Creating a waterfall
(d) Stopping erosion
Ans: (a)
Dams are constructed mainly for purposes such as generating electricity, providing water for irrigation, and controlling floods.

(iv) Which of the following is a water conservation method?
(a) Running the tap while brushing teeth
(b) Fixing leaky faucets
(c) Watering plants during the hottest part of the day
(d) Using a hose for car washing
Ans: (b)
Water conservation involves using water wisely and preventing wastage. Fixing leaky faucets is a way to save water.

(v) Where do underground water reserves called aquifers store water?
(a) In clouds
(b) In lakes
(c) In rivers
(d) In porous rock layers
Ans: (d)
Aquifers are underground layers of rock or sediment that can hold water. They are a vital source of freshwater for many regions.

Q3: True or False.

(i) Water cycle is a continuous process of water movement on Earth.
Ans: True
The water cycle is an ongoing natural process that involves the movement of water through evaporation, condensation, and precipitation.

(ii) All the water on Earth is drinkable without any treatment.
Ans: False
Not all water on Earth is drinkable without treatment. Water from various sources, even natural ones, can contain impurities or contaminants that require purification.

(iii) Desalination is the process of making freshwater salty.
Ans: False
Desalination is the process of removing salt and other impurities from seawater to make it suitable for drinking and other purposes.

(iv) Lakes and rivers are examples of surface water.
Ans: True
Lakes and rivers are examples of surface water, which is water found on the Earth's surface in lakes, rivers, streams, and reservoirs.

(v) Precipitation includes water falling in the form of dew.
Ans: True
Precipitation includes various forms of water falling from the atmosphere to the ground, including rain, snow, sleet, and hail. Dew is not considered precipitation.

Q4: Match the Following.

Ans:

Q5: Short Answer Questions.

(i) Explain the water cycle in your own words.
Ans: The water cycle is the continuous process of water moving from the Earth's surface to the atmosphere and back again. It involves evaporation, where water turns into vapor due to heat; condensation, where vapor turns into water droplets to form clouds; and precipitation, where water falls from clouds as rain, snow, sleet, or hail. This water then flows into rivers, lakes, and oceans, and the cycle repeats.

(ii) Why is it important to conserve water? Give two reasons.
Ans: Water conservation is crucial for several reasons. Firstly, freshwater is a finite resource, and by conserving water, we ensure its availability for future generations. Secondly, water scarcity is a global issue, and conserving water helps address this problem. Additionally, saving water reduces energy consumption, as less water needs to be treated and transported, leading to environmental and economic benefits.

(iii) Describe the process of desalination.
Ans: Desalination is the process of removing salt and other impurities from seawater to make it suitable for drinking and other uses. This is typically done through methods such as distillation or reverse osmosis, which involve separating the salt and minerals from the water molecules. Desalination is important for regions with limited freshwater sources but abundant seawater.

(iv) How do dams benefit society and the environment?
Ans: Dams have multiple benefits for society and the environment. They help manage water resources by regulating river flow, which can prevent floods and ensure a steady water supply for irrigation and consumption. Dams also generate electricity through hydropower. However, they can lead to habitat disruption and alter ecosystems, so their construction requires careful planning.

(v) Name and describe two sources of surface water.
Ans: Two sources of surface water are rivers and lakes. Rivers are flowing bodies of water that usually originate from mountains or hills and flow into oceans, seas, or other rivers. Lakes are large bodies of standing freshwater, often surrounded by land. Both rivers and lakes serve as important sources of water for various human activities and ecosystems.