A fictional element has two naturally occurring isotopes with the following natural abundances: Isotope-18 = 40.0%. Isotope-20 = 60.0%. Which statement is true for this element?
a. The element has a higher atomic mass than Isotope-18.
b. The element has a lower atomic mass than Isotope-18.
c. The element has a stable atomic structure.
d. The element is a noble gas.
