GCSE Chemistry

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GCSE Chemistry
2012-05-29 11:37:52
mock exam corrections

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  1. gold rings often aren't made from 100% gold state two reasons why
    • because pure gold has a regular layer of atoms that can slide over each other making pure gold soft
    • gold is a rare metal in the earths crust . So it is expensive
  2. this table shows the percentages of some gases in the exhaust from a petrol engine
    nitrogen 68
    carbon dioxide 15
    carbon monoxide 1
    oxygen 0.75
    nitrogen oxides 0.24
    hydrocarbons 0.005
    sulphur dioxide 0.005
    other gases
    what is the name of the other compound that makes up most of the other gases in the table
    water vapour
  3. state how nitrogen oxides are produced in a petrol engine
    the nitrogen and oxygen in the air combine , this is because there are high temperatures in the engine
  4. most scientists are concerned about the carbon dioxide realeased from burning fossil fuels such as petrol suggest why
    • because carbon dioxide is a greenhouse gas and leads to global warming
    • the amount of carbon dioxide in the atmosphere is increasing
  5. what did Wenger mean by continental drift
    he thought the continents were once joined , however now the continets are moving apart
  6. give one environmental impact of recycling aluminium cans and one ethical or social impact of recycling aluminium cans
    • environmental = less energy is needed to extract aluminium so less pollution
    • ethical or social = creates employment
  7. to make margerine from olive oil the percentage of unsaturated fats needs to be decreased why
    so that it has a higher melting point and is harder