Question

What is the amount of a certain isotope that occurs in a natural sample of an element

Answer 1

Answer:Relative abundance.

Step-by-step explanation:

Relative abundance is the percentage of a particular isotope that occur in nature.

Answer 2

I believe it is the percent abundance. Isotopes are atoms of the same element with similar atomic number but different mass number. Natural abundance is the abundance of isotopes of a chemical element as naturally found on the planet. The relative atomic mass of these isotopes is the atomic weight listed for the element in the periodic table.