Knowledge N Fact4u

Why is plastic not used in home construction ? •Plastic materials are used in several ways in home construction. Plastic has useful properties such as water resistance, corrosion resistance, electrical insulation, and durability. •Here we are using the common meaning of the word "plastic": a synthetic moldable solid. Among the uses of plastic in home construction are: •Sewage pipes. These are increasingly being made out of plastic such as PVC instead of metal because PVC is cheap, corrosive resistant, light, and somewhat flexible. •Water supply lines. These are increasingly being made out of plastic such as PEX because PEX is cheap, strong, and flexible. The relatively high flexibility of PEX leads to better water flow and quicker installation. •Fuel supply lines. •Electrical conduits. These are channels that carry various electrical wires. •Insulating coating on electrical wires. •Housewarp. This is the weather barrier that is placed just behind the...

Why is lead used in pencils even though lead is poisonous ? •The core of a pencil does not contain lead and never has. Pencils contain a form of solid carbon known as graphite.  •According to a study, the graphite pencil was first developed and popularized in the 1600's.  •The first users of graphite simply dug this mineral out of the hills and discovered it could be sawed into sticks and used as an excellent writing tool.  •During the 1600's, no one knew the chemical nature of this material, as chemistry itself was still in its infancy. •Since this writing material behaved similar to metallic lead, but had a darker color, people began calling it "black lead".  •Eventually, the name of the core of the pencil got shortened to "lead". In 1779, German chemist K. W. Scheele finally determined pencil lead to be composed of pure carbon.  •A decade later, A. G. Werner decided that this carbon material needed a new name and proposed the name "graphi...