-The invisible gaseous substance surrounding the earth, a mixture mainly ofoxygen and nitrogen.– Air in its liquid state, intensely cold and bluish, obtained by cooling andcompression.-Rainfall made sufficiently acidic by atmospheric pollution that it causesenvironmental harm, typically to forests and lakes. The main cause is the industrialburning of coal and other fossil fuels, the waste gases from which contain sulfur andnitrogen oxides, which combine with atmospheric water to form acids-A layer in the earths stratosphere at an altitude of about 10 km (6.2miles) containing a high concentration of ozone, which absorbs most of theultraviolet radiation reaching the earth from the sun.-Each of two or more different physical forms in which an element canexist. Graphite, charcoal, and diamond are all allotropes of carbon
Priestley (1733-1804) was hugely productivein research and widely notorious inphilosophy. He invented carbonated waterand the rubber eraser, identified a dozen keychemical compounds, and wrote one of thefirst comprehensive treatises on electricity.But the world recalls Priestley best as theman who discovered oxygen, the activeingredient in our planets atmosphere. In theprocess, he helped dethrone an idea thatdominated science for 23 uninterruptedcenturies: Few concepts "have laid firmerhold upon the mind," he wrote, then that air"is a simple elementary substance,indestructible and unalterable."
79%20%0.03% 5%0.9%0.002%Composition by volume of clean airNitrogen 78-79%Oxygen 20%Carbon dioxide 0.03%Water vapor 0-5%Argon 0.9%Neon and Helium 0.002%
The liquid nitrogen boils at the bottom of thecolumn. Gaseous nitrogen rises to the top,where it is piped off and stored. Liquid oxygencollects at the bottom of the column. The boilingpoint of argon - the noble gas that forms 0.9%of the air - is close to the boiling point ofoxygen, so a second fractionating column isoften used to separate the argon
is a rain or any other form ofprecipitation that is unusually acidic, meaning that itpossesses elevated levels of hydrogen ions (low pH).
Once they reach the stratosphere, the sun’sultraviolet rays break down thecompound, thus releasing chlorine.Thisresulting chlorine is what damages theozone in a repetitive process. In fact, onechlorine atom will continue to destroy theozone for as long as two years.
Answer:Since the banning of CFC in industry (Montreal Protocol, 1989),ozone depletion has mostly stopped with some signs that levels are increasing.Scientists believe that ozone will return to its pre-CFC level by about 2050.Ways to Protect the Ozone Layer:Minimize high altitude aircraft flights (oxygen reduction and water vapor deposition)Minimize rocket flights (water vapor deposition)Decrease / control releases of high temperature steam / moisture to the atmosphereEliminate production and release of known ozone depleting chemicals (such as CFCsand HCFCs) where remotely possible. Subsidize production of safer alternatives wherepossible.Establish controls to assure that new compounds to be used in high volume, aresurveyed for effect on ozone.