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SOLUTION TO EXERCISE 5

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SOLUTION TO EXERCISE 5


0.1% - i.e. 0.001 - of the comet's volume is vaporized.  The volume of
the comet is 1 cubic kilometer = (100,000 cm)^3 = 10^15 cubic centimeters.
The density of ice is 0.92 g/cm^3.  The molecular weight of water is 18,
meaning that a mole (6 * 10^23) of water molecules has a mass of 18 grams.
So the total number of molecules vaporized is

   0.001 * 10^15 cm^3 * 0.92 g/cm^3 * 6 * 10^23
   -------------------------------------------- = 3.1 * 10^34 
                    18 g