You plan to use the water displacement method to determine if a ring is pure silver. Each of these tools is
required, EXCEPT:
a. A balance
b. A stopwatch
c. A measuring cup filled with water
d. A density of elements chart

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Is there any opitions? if you have the periodic table, the noble gases are 8a family, the halogen are the 7a family, and the nonmetal are  carbon, nitrogen, phosphorus, oxygen, sulfur, selenium, fluorine, chlorine, bromine, iodine and astatine.