The average atomic mass recorded on the periodic table for cobalt is 58.933 u. this indicates that the most abundant isotope of cobalt is
a.) cobalt-57
b.) cobalt-58
c.) cobalt-59
d.) cobalt-60

The average atomic mass of the element is the sum of the products of the percentage abundance of isotope and its mass number. Therefore, for atomic mass equal to 58.933, the most abundant isotope is cobalt-59. Thus, the answer is letter C. 

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