Calculate the reported average elemental atomic mass of $O$ if the naturally occurring isomers are ${}^{16}O,{}^{17}O,and{}^{18}O$. Their masses and abundance are as follows:
$$\begin{array}{ccc}\text{Isotope}& \text{Atomic Mass}& \text{Isotopic Abudance}\\ {}^{16}O& 15.995& 99.76\%\\ {}^{17}O& 16.999& 0.04\%\\ {}^{18}O& 17.999& 0.2\%\end{array}$$

Q. Oxygen occurs in nature as a mixture of isotopes ${}^{1}6O$, ${}^{1}7O$ and ${}^{1}8O$ having atomic masses of 15.995 u, 16.999 u and 17.999 u and relative abundance of 99.763%, 0.037%, and 0.200% respectively. What is the average atomic mass of oxygen?

Q. Calculate the reported average elemental atomic mass of $Mg$, if the naturally occurring isomers are ${}^{24}Mg,{}^{25}Mg,and{}^{26}Mg$. Their masses and abundance are as follows:
$$\begin{array}{ccc}\text{Isotope}& \text{Atomic Mass}& \text{Isotopic Abudance}\\ {}^{24}Mg& 23.98504& 78.70\%\\ {}^{25}Mg& 24.98584& 10.13\%\\ {}^{26}Mg& 25.98259& 11.17\%\end{array}$$

Q. Calculate the reported average elemental atomic mass of $Mg$, if the naturally occurring isomers are ${}^{24}Mg,{}^{25}Mg,and{}^{26}Mg$. Their masses and abundance are as follows:
$$\begin{array}{ccc}\text{Isotope}& \text{Atomic Mass}& \text{Isotopic Abudance}\\ {}^{24}Mg& 23.98504& 78.70\%\\ {}^{25}Mg& 24.98584& 10.13\%\\ {}^{26}Mg& 25.98259& 11.17\%\end{array}$$

Q. The number of water molecules differing in molecular mass formed by hydrogen isotopes and ${}^{1}H,{}^{2}H,{}^{3}H$ and oxygen isotopes ${}^{16}O,{}^{17}O,{}^{18}O$ is _________________.

Q. An element is represented by ${}_Z{X}^A$, where Z is atomic number which is also equal to number of proton, A is mass number and X is symbol of the element.
Mass number (A) = Number of protons (Z) + Number of neutrons.
Isotopes: Atoms having same number of proton
Isobar: Elements having same mass number
Isotones: Elements having same number of neutron (A-Z)

The sum of the number of electrons, protons and neutrons in the three isotopes ${(}^{16}O{,}^{17}O{,}^{18}O)$ of oxygen is: