Which of the given relations about the above elements are correct.
I) ${}^{12}C$
II) ${}^{14}C$
III) ${}^{14}N$
IV) ${}^{16}O$

The correct option is C

II and IV are isotones

Nuclei with the same number of protons but a different number of neutrons are called Isotopes.

Nuclei with the same number of neutrons but a different atomic number are called Isotones.

Nuclei with same mass number are called Isobars.

$\begin{array}{cccc}\text{Element}& \text{Neutron no.}& \text{Proton no.}& \text{Mass no.}\\ {}^{12}C& 6& 6& 12\\ {}^{14}C& 8& 6& 14\\ {}^{14}N& 7& 7& 14\\ {}^{16}O& 8& 8& 16\end{array}$

${}^{12}C\text{and}{}^{14}C$ have same Proton number but different Neutron number so they are isotopes

${}^{14}N\text{and}{}^{14}C$ have same mass number so they are isobars.

${}^{14}C\text{and}{}^{16}O$ have same number of neutrons so they are isotones.