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  1. 1. Merelita Cagi
  2. 2. Merelita Cagi 1. Pure water can exist in three different forms. What are they? - Solid or Ice - Vapor or Steam - Liquid or water 2. With reference to the water cycle, how is salt water converted to fresh water under atmospheric conditions? Water evaporation - water evaporates from the oceans, leaving the salt behind, and forms clouds in the sky, this precipitates out as fog and mist, rain, sleet, snow, running into streams, rivers, lakes and back to the ocean. 3. Given consideration to question2, name 3 basic forms of obtaining fresh water? - Filtering through the earth to vast underground porous rocks called aquifers. - Simple installation of a pump by the side of a river a stream supplies the water for use. - Building dams in valleys and creating storage lakes. 4. Name four characteristics of a safe drinking water - Clear and perfectly transparent - Free from sediment of suspended matter - Bright and sparkling - Odorless and well aerated 5. Name two types of filters used to filter portable water - Mechanical Filter : Gravity filters and pressure filters - Domestic Filters: Chemical filters and mechanical and straining filter 6. At what temperature is water most dense? -Maximum density is at 4o C
  3. 3. Merelita Cagi 7. Name four impurities that may be present in water supplies? - Turbidity and sediment: is always unpleasant drinking water (muddy, thick). Imparts an unsightly appearance to water and unless removed by coagulation and/or filtration, deposits in water pipes, etc. - Organic matter: organic matter often gives rise to color formation and bad taste, as it favors the development of such organisms as algae, fungi and bacteria, which attach themselves to pipe walls. - Tastes and odors: these are usually considered together, because the removal of one will result in the removal of the other. Principal cause of taste and odors in public water supplies include such matter as algae, sewerage, etc. Removal is achieved by either aeration, chlorination, ammonization, absorption. Absorption being the most effective. - Dissolved gases: such as carbon dioxide and oxygen accelerate corrosion in water pipes, particularly on hot water and streamlines. Aeration and neutralization will eliminate CO2 problems, de-aeration and corrosion inhibitors will solve excess O2 problems. 8. There are two forms of hardness found in water. Name these forms and explain how each can be removed? -Temporary hardness: this can be removed by boiling [causes carbonic acid to be driven off and the bicarbonate of lime or magnesia is precipitated], addition of quicklime [presence of the lime expels carbon dioxide] and the use of zeolites which is known as the base exchange method. Zeolite is a chemical compound containing sodium. - Permanent hardness: The addition of caustic soda, addition of lime and zeolites. Note that permanent hardness cannot be removed by boiling. 9. State in your own words how water that is collected at dams is distributed to the consumer in your local area? Installation of water pump carries raw water from Rewa River to the Water treatment plant, where it is screened and chemicals are added then passed to a dam for sedimentation and water has been passed on to the filter on filter beds, after this then it will be passed on for a final dam for chlorination and then to storage tanks, to
  4. 4. Merelita Cagi reservoirs. From reservoirs to pipes which carries portable water to consumers which is safe to drink.