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Atmosphere: The envelope of air around the earth that extends many kilometres above its surface.Active air: The one-fifth portion of air that is used up in burning and supports combustion, later named oxygen.Inactive air: The remaining four-fifths portion of air that does not support burning or life, later named nitrogen.Nitrogen cycle: The cyclic process of continuous circulation of nitrogen through living and non-living components in nature.Nitrogen fixation: The process of converting free atmospheric nitrogen into soluble nitrates that plants can absorb.Nitrate assimilation: The process by which plants absorb nitrates from the soil through roots and convert them into plant proteins.Ammonification: The process by which proteins in dead organisms and excreted animal wastes are converted into ammonium compounds by putrefying bacteria and fungi in the soil.Nitrification: The process of converting ammonium salts in the soil first into nitrites and then into nitrates.Denitrification: The process by which a part of soil nitrates is converted by Pseudomonas bacteria into nitrogen gas that escapes into the atmosphere.Thermal decomposition: The process of breaking up a chemical compound into its components upon heating.Downward displacement of water: A gas collection method used for insoluble or slightly soluble gases, where the gas collects in a jar by displacing water downwards.Oxidation: The process of oxide formation that occurs when metals, non-metals, or metal sulphides combine with oxygen.Fast oxidation: A process where a substance combines rapidly with oxygen to release both heat and light energy, such as burning or combustion.Ignition temperature: The minimum temperature to which a substance must be heated in order to catch fire and burn.Slow oxidation: A process where a substance combines slowly with oxygen over a period of time, releasing a small amount of heat and no light energy.Rusting: A slow oxidation process where an iron object exposed to air and moisture forms a brown flaky substance called hydrated ferric oxide (rust).Respiration: A slow, natural process occurring at body temperature where living organisms use oxygen for the breakdown of digested food to release energy.Photosynthesis: The process in plants where carbon dioxide reacts with water in the presence of sunlight and chlorophyll to form glucose and oxygen.Oxygen cycle: The continuous circulation of oxygen through living organisms and chemical processes in the atmosphere.Noble gases: Gases present in traces in the air that do not react chemically with any other substance.Humidity: The amount of water vapour present in the air, which varies from place to place and season to season.Precipitation: The process where water vapour in the air condenses continuously and reaches the earth’s surface in the form of rain, hail, snow, dew, and mist.Water cycle: The continuous movement of water from the earth’s surface as water vapour to the atmosphere and from the atmosphere back to the earth’s surface.Air pollution: The contamination of air with unwanted substances that have harmful effects on both living and non-living things.Air pollutants: The harmful and unwanted substances, such as toxic gases, smoke, and dust, that contaminate the air.Particulate matter: A mixture of solid particles or liquid droplets, including dust, pollen, soot, and smoke, that remain suspended in the atmosphere.Acid rain: Rain that is acidic in nature, produced when acidic oxides of sulphur and nitrogen react with water and oxygen in the air to form acids.
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Chapter: 07. Air And Atmosphere
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