Water is one of the natural resources that can be found in sufficient quantities. It is a necessary component for the survival of life on Earth. It is commonly used for drinking, washing, bathing, cleaning, cooking, irrigation, and other industrial and domestic purposes.
There are numerous water sources. Water covers approximately 97 %of the Earth’s surface. The three primary water sources are:
- Rainwater.
- Groundwater
- Surface water
Life originated from water, hence nearly all organisms need water to exist and survive. Water also forms the base for all living organisms. As much water is lost from our body, the same or more needs to be replenished.
- Water is used in everyday life for drinking, farming, construction, agriculture, industries, and hospitals.
- Water boosts metabolism, and helps in blood circulation.
- Helps create saliva and provides oxygen to cells of the body.
- It houses different aquatic creatures.
- Used as a means of transportation.
Download PDF of Class 7 Chemistry Worksheet on Chapter 16 Water A Precious Resource – Set 3
CBSE Class 7 Chemistry Chapter 16 Water A Precious Resource Worksheet – Set 3
Download PDQ1. Out of the given options, choose the solid form of water is–
a.) fog
b.) ice
c.) dry ice
d.) mist
Correct Answer– (b.) ice
Q2. Which of the following is not an effect of acute scarcity of water on plants?
a.) Shortage of food
b.) Shortage of oxygen
c.) Shortage of carbon dioxide
d.) Shortage of rainfall
Correct Answer– (c.) Shortage of carbon dioxide
Q3. Which of the following does not allow water to seep in?
a.) Forest land
b.) Soil
c.) Cement floor
d.) Sand
Correct Answer– (c.) Cement floor
Q4. Which of the following is not a reason for water depletion?
a.) Rainwater harvesting
b.) Industrialisation
c.) Deforestation
d.) Aforestation
Correct Answer– (a.) Rainwater harvesting and (d.) Aforestation
Q5. Out of the given options, choose the one which is the purest form of water.
a.) River water
b.) Sea
c.) Rainwater
d.) All of the above
Correct Answer– (c.) Rainwater
Q6. Fill in the blanks:
a.) The process of changing water vapour into water is called ___.
b.) ___ may be caused due to excessive rains.
c.) The process of water/snow falling out of the sky is called ___.
Answer.
a.) The process of changing water vapour into water is called condensation.
b.) Floods may be caused due to excessive rains.
c.) The process of water/snow falling out of the sky is called precipitation.
Q7. State True or False.
a.) Increasing population is one of the reasons for the water table being depleted.
b.) Ice is heavier than water.
c.) Snow and ice are liquid forms of water.
Answer.
a.) True
b.) False
c.) False
Q8. What is drip irrigation?
Answer. Drip irrigation is a low-cost water-use method. To save water and nutrients, this technique involves allowing water to drip slowly to the roots of plants, either above the soil surface or buried below the surface. The goal is to minimise evaporation while directing the water into the root zone. Drip irrigation systems distribute water through valves, pipes, tubing, and emitters.
Q9. What are the advantages of water harvesting?
Answer. The advantages of rainwater harvesting are:
- It is cost-effective.
- Conserves water.
- A source of water for landscape irrigation.
- It is a simple method and easy to practice.
- It reduces soil erosion and pollution of water bodies due to fertilisers and pesticides.
Q10. Define bawris.
Answer. One of the old rainwater management approaches is Bawris.
Q11. Water is available in different forms. Explain.
Answer. Water in nature exists in three forms:
- As solid- In solid, water exists as snow and ice.
- As liquid– In liquid, water exists as water.
- As gas– In gaseous form, it exists as water vapour.
Q12. Define rainwater harvesting.
Answer. Rainwater harvesting is the process of collecting and storing rainwater for later use rather than letting it runoff. The rainwater harvesting system is one of the most effective and widely used methods for water conservation. The main source of concern at the present time is the scarcity of high-quality water.
Q13. State different uses of water.
Answer. Some of the uses of water are as follows:
● In the home, water is used for drinking, cooking, washing utensils, cleaning the floor, brushing teeth, bathing, washing clothes, flushing toilets, and watering plants. These are the water uses in the home. Water is also used for drinking by animals.
● In agriculture, water is used to grow food.
● Water is used in manufacturing paper, cloth, medicines, and chemicals, among other things.
● Electricity is generated using water.
● Water from rivers and the sea aids in dispersing seeds from various plants and trees.
Q14. What can you do to save water?
Answer. The following are some ways that we, as individuals, can conserve water:
i.) Taking baths in a bucket and avoiding showers.
ii.) Ensure water from overhead tanks does not overflow
iii) Turn off the water while brushing our teeth.
iv.) Washing fruits and vegetables in a water bowl instead of under running water.
v.) Using the water used to wash vegetables to water garden plants.
vi.) Using a bucket or very less water to wash vehicles rather than pipes.
Q15. What is groundwater? What are its sources of water?
Answer. Rainwater, as well as water from other sources such as rivers and ponds, seeps through the soil, filling empty spaces and cracks deep beneath the ground. Infiltration is the process by which water seeps into the ground. Groundwater is recharged through the infiltration process.
Q16. Can deforestation be considered as a reason for the depletion of the water table? If yes, explain why?
Answer. Yes, deforestation is one of the reasons for the depletion of the water table.
Due to the growing population and industrialisation, there is a vast requirement of land for building houses, power plants and industries. Cutting down forests for building these is reducing open spaces. This, in turn, reduces rainwater seepage into the ground.
Transpiration allows forests to transport large amounts of water into the atmosphere. As a result of the deforestation, there is no rain in that area, which flows away as river water and causes permanent drying.
Q17. From where do the following usually get water? In which form is water present in them?
a.) Clouds
b.) Plants
c.) Mountain tops
d.) Aquifer
e.) Animals
Answer.
| Source | Form | |
|---|---|---|
| a.) Clouds | Land | Liquid |
| b.) Plants | Soil | Liquid |
| c.) Mountain tops | Atmosphere | Solid |
| d.) Aquifer | Rain, Underground water | Liquid |
| e.) Animals | Waterbodies | Liquid |
Q18. Explain the different processes involved in the water cycle.
Answer. The processes involved in the water cycle are as follows:
i.) Evaporation
The sun is the ultimate energy source, and it drives the majority of evaporation on Earth. In this process, the water from the earth’s water bodies evaporates, changing its state from liquid to water vapour.
ii.) Transpiration – Plants take water from the soil to prepare their own food and other life processes. They release excess water into the air in the form of water vapour by the process of transpiration.
iii.) Condensation – The evaporated water moves higher from the surface of the Earth, where it starts to cool down. This water vapour condenses to form tiny water droplets, which float in the air to form clouds or fog.
iv.) Precipitation – All these droplets collect in the clouds, and when clouds become heavy, this water comes down as rain through precipitation. If the air is too cold, the water drops can become snow or hail and may settle on the top of a mountain.
v.) Surface run-off – Some rainwater is absorbed by the soil and settles down as groundwater. Most rainwater flows down the hills and mountains to collect into rivers, lakes or streams.
Q19. Why is water a precious resource?
Answer. Water is essential for all life on Earth. Water is required for both plant and animal survival. Water is required for food security, animal security, organic life, industrial production, biodiversity conservation, and environmental preservation. Our body uses water to regulate temperature and perform other bodily functions in all of its cells, organs, and tissues. Thus, water is a precious resource.
Q20. Why is there a need to conserve water?
Answer. Water conservation is necessary because –
i. The level of groundwater is decreasing due to climate change. Because of the falling level, this results in limited water use. So, we should conserve water to raise the groundwater level and avoid a water shortage when the underground water level drops dramatically.
ii. The population is growing at an alarming rate, while water resources are depleting. To avoid water scarcity, we must conserve more and more water while also preventing it for future generations.
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