pollution

• What is the approximate percentage of nitrogen in the atmosphere?

  About 80%
• What is the approximate percentage of oxygen in the atmosphere?

  About 20%
• What gases are present in small proportions in the atmosphere?

  Carbon dioxide, water vapour, noble gases
• How did algae and plants contribute to the oxygen in the atmosphere?

  They produced oxygen through photosynthesis
• What is the photosynthesis equation that represents oxygen production?

  6CO2 + 6H2O → C6H12O6 + 6O2
• When did algae first produce oxygen?

  About 2.7 billion years ago
• What happened to the percentage of oxygen over the next billion years?

  It gradually increased to enable animal evolution
• What is one theory about the Earth's early atmosphere?

  It was formed by volcanic activity releasing gases
• What gases may have been present in the early atmosphere?

  Mainly carbon dioxide with little or no oxygen
• How did carbon dioxide levels decrease in the atmosphere?

  Through photosynthesis and ocean absorption
• What is limestone primarily composed of?

  Calcium carbonate
• How is coal formed?

  From thick plant deposits buried and compressed
• What produces crude oil and natural gas?

  Deposited plankton covered and compressed over time
• What are two sources of nitrogen in the atmosphere?

  Volcanoes and denitrifying bacteria
• What human activities contribute to greenhouse gas increases?

  Combustion of fossil fuels and deforestation
• What is the carbon footprint?

  Total greenhouse gases emitted over a product's life
• What is one action to reduce the carbon footprint?

  Increased use of alternative energy supplies
• What is the greenhouse effect?

  It maintains Earth's temperatures for life
• What is the process of the greenhouse effect?

  UV radiation enters, Earth absorbs, re-emits IR
• What gases are considered greenhouse gases?

  Water vapour, carbon dioxide, methane
• What correlates with the increase in carbon dioxide over the last 100 years?

  Increased use of fossil fuels
• What is a major cause of climate change?

  An increase in average global temperature
• What are potential effects of global climate change?

  Sea level rise, severe storms, rainfall changes
• What are some problems of reducing the carbon footprint?

  Lack of public information and scientific disagreement
• What is complete combustion of hydrocarbons?

  Occurs with a plentiful oxygen supply
• What is the equation for complete combustion of methane?

  CH4 + 2O2 → CO2 + 2H2O
• How are nitrogen oxides produced?

  By burning fuels at high temperatures
• What happens during incomplete combustion?

  Produces carbon monoxide and soot
• What is carbon monoxide?

  A toxic, colorless, and odorless gas
• What is sulfur dioxide produced from?

  Burning sulfur impurities in fuels
• What pollutants are released during combustion?

  Carbon dioxide, water vapour, carbon monoxide
• What health problems can sulfur dioxide and nitrogen oxides cause?

  Respiratory problems in humans
• What is acid rain caused by?

  Sulfur dioxide and nitrogen oxides
• What is the advantage of complete combustion?

  Less soot and more heat released
• What is the nature of combustion of hydrocarbon fuels?

  It is an exothermic reaction
• What happens to carbon and hydrogen during combustion?

  They are oxidised