Final answer:
The spectra of the oldest stars show the most heavy elements. The abundance of heavy elements in stars varies, with the Sun and most stars having about 1-4% of their mass in heavy elements, while in globular clusters and very old stars, the heavy-element abundance can be much lower.
Step-by-step explanation:
The spectra of the oldest stars show the most heavy elements. In the Sun and most stars, the abundance of elements heavier than hydrogen and helium is typically 1-4% of the star's mass. However, in globular clusters and some very old stars, the heavy-element abundance can be significantly lower, often less than one-hundredth or even one ten-millionth the concentrations found in the Sun.