If the radius of first Bohr orbit is $r$, then the radius of the second Bohr orbit will be

$$ \text { Match the following types of nuclei with examples shown } $$

$$ \begin{array}{|l|l|} \hline \text { Column-I } & \text { Column-II } \\ \hline \text { A. Isotopes } & \text { i. } \mathrm{Li}^7, \mathrm{Be}^7 \\ \hline \text { B. Isobars } & \text { ii. }{ }_8 \mathrm{O}^{18},{ }_9 \mathrm{~F}^{19} \\ \hline \text { C. Isotopes } & \text { iii. }{ }_1 \mathrm{H}^1,{ }_1 \mathrm{H}^2 \\ \hline \end{array} $$

Which of the following statements is incorrect with reference of 'Nuclear force'?