i.If it does not rain in a region for a year or more. The soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, the soil becomes dry. The level of water in wells and in ponds of the region goes down and some of them may also became scarce. This may lead to drought.
ii.Seas, Oceans, Rivers, Springs, Tube wells, etc.
iii.Rivers flowing from different places bring water containing dissolved salts and minerals into the sea. Sea water is continuously evaporated by the heat of sun. This evaporated water forms clouds and again fall on the earth as rain. This rain water again dissolves salts into it and goes into the sea. Thus, the amount of salts in sea water goes in increasing.
iv.Water cycle is important to us because of the following:
a. It restores the supply of water in nature.
b. It regulates the temperature of atmosphere.
i.Areas covered with concrete reduce the seepage of rain water into the ground and this reduces the availability of ground water.
ii.There is need for conserving water because With a change in climate, the level of groundwater is decreasing. This results in limited use of water because of the fallen level. So, we should conserve water in order to increase the groundwater level and accomplish the shortage of water when the underground water level goes down drastically.The population is increasing day by day at an enormous amount and water sources are decreasing. To prevent the scarcity of water we should conserve more and more water and prevent it for the next generations as well.
iii.When we keep a cooled bottle of water taking out from a refrigerator, we notice some puddles of water around it. This is due to the water – vapour near the surrounding atmosphere, condenses and deposits around the cooled water bottle. Water vapour always remains in the atmosphere.
iv.No, on such a day we will use less amount of water.
v. Plants lose their extra water continuously from the tiny openings present in their leaves. This process is known as transpiration.
vi.First, take a clean glass and put some ice cubes in it. Keep it in the open air. After some time, small droplets of water will be observed on the outer surface of the glass. This is because water vapour in the air comes in contact with cold surface of glass and condenses. These droplets of water are due to condensation of water vapour present in the air.
vii.(i) Washing a dozen clothes
(ii) Irrigating a crop field
viii.When we breathe on the spectacles, water vapour comes out from our breathe, and they condense into water droplets when they come in contact of glass, because the glasses are cooler that the water vapour. Hence, the glasses become wet due to water puddles.
ix.There is a continuous evaporation of water from surfaces of sea, rivers, lakes, etc. As we go higher from the surface of the earth, it gets cooler. When the air moves up, it gets cooler and cooler. At sufficient height, the air becomes so cool that the water vapour present in it condenses to form tiny drops of water called droplets. It is these tiny droplets that remain floating in air and appear to us clouds.
x. If it does not rain in a region for a year or more. The soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, the soil becomes dry. The level of water in wells and in ponds of the region goes down and some of them may also became scarce. This may lead to drought.
xi.There is yet another process through which water vapour gets transferred into the air. This process involves plants. All plants need water to grow. Plants get this water from the soil, which is absorbed from it by their roots. A part of this water is used by them to prepare their food. Some water is retained by different parts of the plants like roots, stem, leaves, flowers and fruits. However, a large part of this water is released by the plants into air as its vapour. Most of the water lost by the plants in this process is through their leaves. This process is known as transpiration. Every plant whether it is in a crop field, a forest, on the roadside or in a kitchen garden transpires to give off water vapour. The amount of water vapour that goes into the air through the process of transpiration is very huge.
xii.Yes, if we want to dry our school uniform quickly, we should spread our clothes near a heater. The reason is that near heater, temperature is more so water evaporation from the clothes will be faster, hence the clothes dry quickly.
The water which is safe for drinking is not available in plenty. Thus everyone should make efforts to save water. We should also minimize the water pollution.
We can minimize water wastage by following methods:
Pollution of water at sources should be minimized.
(i)The ground water is actually rain water which mainly comes from seepage of water accumulated under the ground. This reserve water under the ground is called ground water
(ii)Rain water percolates into the soil and reaches under the ground where water quantity increases and air decreases.
(ii)Open wells are fed by ground water. Ground water is the source of many lakes as well The more land pumps or tube wells that are used in an area, the deeper we need to dig to find this ground water.
a. Water is essential for life. There are many sources of water, but water obtained from these sources are not fit for drinking. To make it safe for drinking, it has to undergo many methods of purification, which is a long process. So, water must be conserved. It means, it should be carefully and economically used.
b. Water is useful in many ways like:
1. For drinking, washing, cooking and other household works.
2. It is used for generation of energy in dams.
3. It is used for irrigation of fields for proper crop yield.
4. It is used in industries.
5. It is used in car to cool radiators.