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4 Starting with a melt of composition An30, trace the crystallization history as the melt cools, crystallizes and solidifies by answering the following questions.At what temperature does the melt begin to crystallize?What is the composition of the first crystals?In general, what happens as the system continues to cool?At a temperature of 1250o, what is the composition and percentage of crystals?What is the composition and percentage of the remaining melt?How has the composition and percentage of each changed as the system cooled from the temperature of initial crystallization?Explain in terms of continuous reactions how this happened?At what temperature does the system become solid rock and what is its final composition?

5 Starting with a solid of composition An70 at 1200o, trace the melting history as the system is heated progressively.At what temperature does it begin to melt?What is the composition of the first melt?In general, what happens to the system as the temperature continues to increase.At a temperature of 1400o, what is the composition and percentage of the remaining melt?What is the composition of the remaining crystals?How has the percentage of each changed and how can this be explained in terms of continuous reactions?At what temperature would the melting become complete and what would be its composition?