GCSE Chemistry (Triple)

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GCSE Chemistry (Triple)
2012-02-17 14:17:22

Chemistry revision
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  1. the outer layer of the earth is a thin rocky layer called the :
  2. the crust is the bit we live on and it is very ..... (it varies between 5km and 50km) and it is surrounded by the ....
    • thin
    • atmosphere
  3. the layer before the crust is the :
  4. the mantle is also made up of rock like the crust but it has a higher :
    density and is a different composotion to that in the crust . the mantle has all the properties of a solid except that it can flow very slowly .
  5. why can the mantle flow
    the mantle is relatively cold and ridgid just below the surface of the crust but deeper down it is hotter and so the mantle can flow slowly . Also radioactive reactions that take place within the core produces heat and convection currents in the mantle allowing the mantle to flow
  6. the core is the :
    centre of the earth and contains iron and nickel , it makes up over half the earths radius
  7. the relatively cold , rigid part of the earth that includes the crust and outer part of the mantle is called the :
  8. what is the lithosphere made up of
    a number of large interlocking pieces called tectonic plates
  9. why do earthquakes and/or volcanic erruptions occur
    at the boundaries between tectonic plates
  10. the earths crust is ... and ..... moving
    • unstable
    • continually
  11. the new theory for the existance of plate tectonics within the earths crust is :
    the features we see on earths (mountians , volcanoes) are caused by plate movement
  12. evdidence for the new theory that the crust is made of plates that move slowly is :
    • the continents fit together like a jigsaw
    • identical plant and animal fossils of the same age have been found in rocks in different continents
    • there are various identical tpes of living creatures found in different continents
    • there are layers of rock on different continents that are of similar ages and that match
    • all the above suggest that countries and continents must have been onced joined and something must have caused them to move apart
  13. the idea that the earths lithosphere moves is not ..... . A.... ...... first suggested it in 1915 . he called the process .... ... . he was trying to explain why South America and America fitted together like a .... and why they had similar ...... and ..... formations . he though tthat the continents moved because of the earths .... . scientist proved that this was not the case so because his explaination of why the plates moved were wrong, his plate movement theory was not taken seriously
    • new
    • Alfred Wenger
    • continental drift
    • jigsaw
    • fossils
    • rock
    • spin
  14. although scientists know where earthquakes and volcanic erruptions are likely to occur (at the boundaries between plates) , they cannot predict exactly when they will occur . predicting an earthquake is most impossible because
    they occur when stresses in the rocks build-up and are suddenly released (so it's a bit like blowing up a balloon up - if you keep blowing you know it will burst but not exactly when) . there is no outward sign of building stresses , so no way of predicting earthquakes
  15. volcanoes often give out warning signs which include : (5)
    • increased seismic activity (waves created by vibrations in the earth)
    • bulges in the ground caused by a build up of magmas below the ground
    • an increase in the amount of sulphur dioxide in the atmosphere which indicates that magma is rising
    • an increase in the temperature of the volcano
    • smoke , fumes and traces of lava coming out of the volcano
  16. when do volcanic warning signs appear in relation to when the volcano will errupt
    sometimes these warning signs occur just a few hours before an erruption but other times they go on for years before the volcano errupts . Hence predicting a volcanic erruption is no more then an intelligent guess
  17. there are 3 ways a plates can move relative to each other :
    • slide past
    • move towards
    • move apart
    • and these movemnts cause different geological features
  18. plates slide past each other this creates . this causes ....
  19. plates move towards each other . if two .... plates collide , fold mountians are formed as rocky material is pushed .... . ia continental plate collides with an .... plate , the ... oceanic plate is forced ... the continental plate . as the oceanic crust is forced down it partially melts and this molten rock then forces its way back up and forms ..... earthquakes alkso occur as the oceanic plate ... past the continenrtal plate on the way down
    • continetal
    • upwards
    • oceanic
    • denser
    • underneath
    • volcanoes
    • rubs
  20. plates move away from each other . when 2 ... plates move away from each other .... rises to fill up the gap and produces new oceanic crust . this process is called sea flooor spreading and it is happening under the middle of the atlantic ocean meaning that america is getting further away from britain by about 5cm every year
    • oceanic
    • magma
  21. explain why tectonic plates move
    heat from radioactive reactions in the core produce convection currents in the mantles this causes the tectonic plates to move
  22. explain why the movemnt of tectonic plates can lead to major diasters
    the tectonic plates collide or rub past each other , this movemnt causes earthquakes and./or volcanic errruptions
  23. in the presence of light , plants carry out .... . in this process ...... .... gas and water reat to form glucose and .... gas . photosynethesis takes in energy and therfor is an ...... process . animals carry out .... in order to produce energy this is an ..... process . it uses up ..... gas a nd produces .... .... gas . carbon dioxide is also produced when fossil .... are burned in air this is speeding up .... warming
    • photosynthesis
    • carbon dioxide
    • oxygen
    • endothermic
    • respiration
    • exothermic
    • oxygen
    • carbon dioxide
    • fuels
    • global
  24. an endothermic reaction is a reaction whereby :
    energy is taken in
  25. an exoothermic reaction is a reaction wherby
    energy is given out
  26. the earths atmosphere has eveolved over .... of years . the early atmosphere contained lots of .... ... and other gases . it also contained lots of .... vapor . when the earth cooled down this .... to liquid water and formed the oceans
    • billions
    • carbon dioxide
    • water
    • condensed
  27. somne of the earliest ... on earth were blue-green .... and these carried out ..... . this process produced ..... . this gas reacted with the substances such as metals to form metal .... when these reactions were finsihed , the .... built up in the atmosphere
    • planst
    • algae
    • photosynthesis
    • oxygen
    • oxides
    • oxygen
  28. the ozone layer formed and stopped too much .... light hitting the earth . animals were able to evolve and carry out ..... . a balance was obrtained and now the oxygen level is about .... of the air in the atmosphere
    • visible
    • respiration
    • one fifth
  29. carbon dioxide is .... than air