Section #: 18.1 Magma

Practice Test
      
  1.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.  
  Hint    
      
  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  
  Hint    
      
  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  
  Hint    
      
  4.When magma reaches Earth's surface it is called __________.  
  a.   rock  
  b.   lava  
  c.   a batholith  
  d.   intrusive  
  Hint    
      
  5.__________ is the internal resistance to flow of a liquid.  
  a.   Viscosity  
  b.   Gravity  
  c.   Specific gravity  
  d.   Weight  
  Hint    
      
  6.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  
  Hint    
      
  7.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  
  Hint    

 
   
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