Final answer:
Without the provided natural abundances for the isotopes of sulfur, it is not possible to accurately determine which sulfur isotope has an average atomic mass closest to the most abundant isotope.
Step-by-step explanation:
To determine which isotope of sulfur has an average atomic mass closest to the most abundant isotope, we need to consider the natural abundances of the isotopes and their respective masses. However, the natural abundances for sulfur's isotopes are not provided in the question, making it impossible to perform an accurate calculation without that data. If the natural abundances were available, we would use a weighted average calculation similar to the one described for chlorine to find which isotope has a mass closest to the average atomic mass presented on the periodic table. This would be done by multiplying the fraction of each isotope's abundance by its mass and summing the results. The sulfur isotope with a mass nearest to this calculated average would be considered the closest to the average atomic mass.