Answer: Option C. -> To understand the importance of water conservation
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C
The ever-growing population of the world has put immense stresson the available freshwater resources. Hence, on 22nd of March every year 'World Water Day' is celebrated in order to promote the importance of water conservation. It helps to take precautions to avoid the acute shortage of water.

Answer: Option D. -> water harvesting
:
D
Water harvesting or rainwater harvesting is the name given to the process of collection of rainwater which would otherwise flow away and get wasted. This water can beuseddirectly for daily activities orto recharge the groundwater.

Answer: Option D. -> is stored between layers of hard rock below ground water.
:
D
When wediginto the ground, we encounter the water table which marks the start of groundwater. As we digdeeper, the groundwater is stored between layers of hard rock below the water table.This deposit of water is called an aquifer. Groundwater can be extracted from aquifersusing a water well.

Answer: Option B. -> False
:
B
Water circulates through water cycle in all three states, solid, liquid and gas.Water cycle involves the process of evaporation of water in which water becomes water vapour (gas) and rises up to form clouds. This water comes back to the earth both in the form of rainwater (liquid)as well as snow (solid).

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Solution: 3 Marks
It's true that about $\frac{3}{4}th$of the earth's surface is filled with water but not all of it can be used by us. The water in seas and oceans are saline water and cannot be used for day to day work. The fraction of usable water is very little and most of it is in the form of snow caps, glaciers. Only 0.006% water is available in the form of rivers, lakes, ponds, and groundwater.
Nowadays, even these sources are being contaminated due to industrial and agricultural activities. Also, due to increasing population and uneven rainfall, there is a shortage of usable water. So, we need to conserve water.

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Freshwater: 1 Mark
Choosing the odd one 1 Mark
Only 2.5% of all the water on Earth isfreshwater.

Agricultural activity is the odd one out.
Rainwater Harvesting and Drip irrigation are methods to conserve water whereas Agricultural activity uses a lot of water.

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Explanation : 3 Marks
It is true that rainfall is a major source of recharging groundwater but collecting rainwater is a good practice.
Generally, rainwater flows through the ground to the rivers, ponds, and lakes. In this process, rainwater seeps into the ground and recharges groundwater. But, in comparison to the amount of water we receive as rainfall, the amount of water we can collect is negligible.
Further, the water we use goes into the sewage which is ultimately treated and let out into rivers. From there it infiltrates thegroundwater.
Moreover, the rainwater can be used for our day to day workand in order to access the same amount of water from the groundwater, we need to dig wells or boreholes to set up a pipe system. So,collecting rainwater is a good habit and the first statement is correct.

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Definition: 1 Mark each
Infiltration: The process of water seeping into the ground through the soil is called infiltration.
Infiltration refills the groundwater.
Aquifer: The spots where the groundwater is stored between layers of hard rocks below the water table are known as Aquifers.
It is a source of fresh water.
Drip Irrigation: Drip irrigation is the process of supplying water to plants by making use of narrow tubings which deliver water directly to the base of the plant.
Drip irrigation is a more efficient way than sprinkling water as it saves a lot of water.

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Factors: 1.5 Marks
Water table: 1.5 Marks
There can be various factors affecting the quality of water. They are:
1) Presence of dissolved chemicals.
2) Presence of dissolved biological compounds.
3) Presence of mud, sand and other effluents.
The various reasons for the depletion of the water table are:
i) Increasing population.
ii) Industrial and agricultural activities.
iii) Deforestation and decrease in the effective area of seeping.

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Analysis of differences: 1 Mark each
In order to win the contest, they should use less water. Let us analyze their usage.
Tom takes a bath in a swimming pool that too daily whereas jerry takes a bath only on Sundays. Swimming pools consume a lot of water ascompared to bathing in the bathroom. So, Jerry conserves more water.
Drip irrigation is a technique to minimize water consumption for irrigation by using underground pipe system which delivers water directly to the base of the plant, whereas sprinklers use jets of water to irrigate which leads to wastage of water. Thus, Jerry conserves more water here too.
Again, collecting rainwater is a good practice to save water, This is called rainwater harvesting. So, Jerry wins this task.
Construction workconsumes a lot of water and moreover increased population increases the use of water. So, in this activity also Jerry wins
Hence, we see that Jerry saves a lot of water in his activities and he wins the competition.