2. Water (chemical formula: H2O) is a transparent fluid which forms the world's streams, lakes, oceans and rain, and is the major constituent of the fluids of living things. As a chemical compound, a water molecule contains one oxygen and two hydrogen atoms that are connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice; and gaseous state, steam (water vapor). It also exists as snow, fog, dew and cloud. Water covers 71% of the Earth's surface.It is vital for all known forms of life. On Earth, 96.5% of the planet's water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of ice and liquid water suspended in air), and precipitation.

4. The uses of water are as follows- 1.Domestic use 2. Irrigation 3. To produce electricity 4.Drinking 5. Bathing, brushing, washing utensils etc. 6. Transportation 7. Aerial Animals 8. Washing clothes 9. Medical 10. Recreation

5. The significance of water to all organisms is that – (1)Water is cooling and has minerals which lets the organism have a boosting energy and a quench of thirst (2)Water is pure and lets the blood circulate more better in the living thing's body (3) Water lets the organism respirate more eagerly because it replaces heat loss in the animal's body. (4) Water cools off the animal's boy from the devouring heat.

6. We can save water in the following ways – 1.Take shorter showers. 2. When washing dishes by hand, don't leave the water running for rinsing. 3. Close the tap while brushing. 4. Water your lawn only when it needs it. 5. Use a broom, not a hose, to clean driveways and sidewalks.

14. Hand pumps are manually operated pumps they use human power and mechanical advantage to move fluids or air from one place to another. They are widely used in every country in the world for a variety of industrial, marine, irrigation and leisure activities. There are many different types of hand pump available, mainly operating on a piston, diaphragm or rotary vane principle with a check valve on the entry and exit ports to the chamber operating in opposing directions. Most hand pumps have plungers or reciprocating pistons, and are positive displacement.

16. THE COMPONENTS OF A HAND PUMP ARE- Riser Main Pipe – This is the vertical pipe through which water is pumped from the water table to the pump head. Usually in the range of 1 ½ inches to 2 ½ inches in diameter, it can be steel pipe sections threaded together or PVC pipe sections usually glued together. In closed-top pump cylinders, the riser main is a smaller diameter than the pump cylinder. In an open-top pump cylinder, the riser main is the same diameter as the pump cylinder. Pump Rod – A solid steel rod about a half inch in diameter that connects the piston assembly in the pump cylinder to the pump handle. Operation of the pump handle moves the pump rod and the piston assembly up and down. Upper Cap – On a closed-top pump cylinder, the upper cap seals the interior of the pump cylinder and defines the limit of motion of the piston assembly. Open-top pump cylinders have no upper cap.

21. The main advantage of hand pumps is that they are one of the most economical and simple solutions for providing a collective supply of drinking water in rural areas and suburban environments. They also help to eliminate the risks of people, and children in particular, falling into open wells. They also improve the conditions of hygiene under which water is drawn off, by eliminating the use of buckets of uncertain cleanliness, thereby limiting diseases associated with contaminated water. The main disadvantage is the required maintenance, the significant physical exertion required for pumping and the potential difficulty of being supplied with spare parts which may not be easy to obtain. A pump requires regular maintenance which must be carried out if the pump is to be used on a sustainable basis. This maintenance may be provided for several models, which should be preferred by local populations. If not, maintenance and repair may have a relatively high cost that people should be fully aware of at the time the choice is made.