Page 91 - ICSE Chemistry 6
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FLOODS AND DROUGHTS

                 Flood

                 When it rains heavily or con  nuously for a number of days, large amount of water gets collected and the
                 rivers overfl ow. This condi  on is known as a fl ood. Floods cause a lot of damage.

                     • Loss of property, death of animals and human s, and extensive damage to crops
                     • Soil erosion
                     • Rise in the level of water in dams, rivers, etc.
                     • Spread of diseases and pollu  on

                 Drought

                 Drought is a period of abnormally low rainfall, leading to shortage of water. It adversely aff ects life.
                 Drought leads to the following.
                     • Lack of food and drinking water               •  Lower groundwater-level in lakes, rivers, etc.

                     • Soil erosion                                  •  Loss of plants and trees
                     • Death of animals                              •  Loss of human lives
                     • Health problems due to poor quality of water

                                                             Terms to Know


                 Groundwater:                Rainwater that gets collected under the ground
                 Water table:                The level of water under the ground
                 Well water:                 The pool of water that is obtained by digging the soil   ll its impervious layer
                 Spring water:               The water which comes out with pressure in the form of spring from any opening
                                             in the earth
                 Water cycle:                The con  nuous circula  on of water from the earth to the atmosphere and back
                                             again
                 Solute:                     A substance that gets dissolved in a liquid
                 Solvent:                    The liquid that dissolves a solute
                 Solu  on:                   A uniform or homogeneous mixture of the solute and solvent
                 Saturated solu  on:         A solu  on which cannot dissolve any more of the solute at a par  cular
                                             temperature
                 Unsaturated solu  on:       A solu  on which can dissolve more of the solute at a par  cular temperature
                 Supersaturated solu  on:    A solu  on which contains more solute than could be dissolved in the solvent
                                             under normal condi  ons
                 Potable water:              Water that is fi t for consump  on

                 Filtrate:                   The liquid that passes through the fi lter paper
                 Residue:                    The par  culate impuri  es which remain on the fi lter paper
                 Loading:                    The addi  on of chemicals to increase the rate of sedimenta  on
                 Chlorina  on:               The process of adding chlorine to water
                 Water pollu  on:            The contamina  on of water by unwanted and harmful substances that cause
                                             harmful eff ects to living and non-living things


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