Harmful and useful effects of gases in the air?

Answer 1

The atmosphere is composed of: Nitrogen (78.8%), Oxygen (20.95%), Argon (0.93%), Carbon dioxide (0.038%) and other gases (percentages by volume proportion). Oxygen in its O3 form protects the planet from ultraviolet radiation (ozone layer) and in its O2 form Oxygen is essential to most forms of life. Ozone is known to cause cancer, and is used to kill bacteries. Nitrogen is part of all biological organisms, taking part in the genetic compounds, and is essential to life. Atmospheric Nitrogen is captured by Nitrogen fixing bacteria which live in the root nodules of many legumionus plants such as peas and beans. When the legumes die the "fixed" Nitrogen in the form of Nitrates is released into the soil where it becomes available for other species of plants and, through the food chain, is also made available to animals. Carbon dioxide is one of the by-products of cellular respiration, and is one of the major greenhouse gases which contribute to global warming. In the process of photosinthesis, carbon dioxid is fixed by the plants, and used to make sugar and celullosis. Argon is one of the Inert or Noble group of gases and as the name of the group implies it doesn't readily take part in any reactions. Other gases such as the various oxides of Sulphur and Nitrogen can dissolve in water to form "Acid Rain" which can cause serious damage to plants, water system and can also be a major cause of erosion of rocks, both in nature and when they have been used as building material. CFCs (Chloro-Fluoro-Carbons) which were once used as a propelant gas in aerosol sprays and a coolant in refrigerators where found to be very damaging to the Earth's ozone layer.