Chapter 2, Problem 2.97P

Dinitrogen monoxide $\left({\text{N}}_{\text{2}}\text{O; nitrous oxide}\right)$ is a greenhouse gas that enters the atmosphere principally from natural fertilizer breakdown. Some studies have shown that the isotope ratios of ${}^{\text{15}}{\text{N to }}^{\text{14}}{\text{N and of }}^{\text{18}}{\text{O to }}^{\text{16}}{\text{O in N}}_{\text{2}}\text{O}$ depend on the source, which can thus be determined by measuring the relative abundance of molecular masses in a sample of ${\text{N}}_{\text{2}}\text{O}$.

(a) What different molecular masses are possible for ${\text{N}}_{\text{2}}\text{O}$?

(b) The percent abundance of ${}^{\text{14}}\text{N is 99}\text{.6\%,}$ and that of ${}^{\text{16}}\text{O is 99}\text{.8\%}\text{.}$ Which molecular mass of ${\text{N}}_{\text{2}}\text{O}$ is least common, and which is most common?