The element oxygen consists of three naturally occurring isotopes: ¹⁶O, ¹⁷O, and ¹⁸O. The atomic mass of oxygen is 16.0 amu. What can be implied about the relative abundances of these isotopes A) More than 50% of all O atoms are ¹⁷O. B) Almost all O atoms are ¹⁸O. C) Almost all O atoms are ¹⁷O. D) The isotopes all have the same abundance, i.e. 33.3%. E) The abundances of ¹⁷O and ¹⁸O are very small.

Question

Quizplus · Accepted Answer

The atomic mass of oxygen is closest to 16.0 amu, which corresponds to the mass number of the most abundant isotope, $^{16}$O. This implies that the abundances of the other isotopes, $^{17}$O and $^{18}$O, must be very small for the average atomic mass to be so close to 16.0 amu.

The Element Oxygen Consists of Three Naturally Occurring Isotopes: 16O

The Element Oxygen Consists of Three Naturally Occurring Isotopes: ¹⁶O