Section #: 18.1 Magma

Practice Test
  1.Rhyolitic magma has the __________ viscosity, the __________ gas content and the __________ silica content of any type of magma.  
  a.   highest, lowest, lowest  
  b.   lowest, lowest, lowest  
  c.   lowest, highest, highest  
  d.   highest, highest, highest  
  2.What type of magma has the lowest silica content and is the least explosive?  
  a.   rhyolitic magma  
  b.   basaltic magma  
  c.   granitic magma  
  d.   andesitic magma  
  3.Where is andesitic magma found?  
  a.   on islands in the Pacific, such as Hawaii  
  b.   at the margins of continents  
  c.   inside of continental crust  
  d.   in the middle of oceanic crust  
  4.When does magma form?  
  a.   when new minerals form due to chemical changes in the rock  
  b.   when temperatures are hot enough to melt rock  
  c.   when grains have been compacted together  
  d.   when volcanoes erupt  
  5.When magma reaches Earth's surface it is called __________.  
  a.   rock  
  b.   lava  
  c.   a batholith  
  d.   intrusive  
  6.Why does magma move up to and through Earth's crust?  
  a.   It is more dense than surrounding rock.  
  b.   It is more viscous than ocean water.  
  c.   It is less dense than surrounding rock.  
  d.   It is cooler than the crust.  
  7.__________ is the internal resistance to flow of a liquid.  
  a.   Viscosity  
  b.   Gravity  
  c.   Specific gravity  
  d.   Weight  

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