The total number of species from the following in which one unpaired electron is present, is . . . . . . $\mathrm{N}_2, \mathrm{O}_2, \mathrm{C}_2^{-}, \mathrm{O}_2^{-}, \mathrm{O}_2^{2-}, \mathrm{H}_2^{+}, \mathrm{CN}^{-}, \mathrm{He}_2^{+}$
$2$
$3$
$4$
$8$
The correct order in which the $O -O$ bond length increases in the following is
Assuming that Hund's rule is violated, the bond order and magnetic nature of the diatomic molecule $B_2$ is
$N_2$ and $O_2$ are converted in to $N_2^+$ and $O_2^+$ respectively. Which of the following is not correct ?
The correct bond order in the following species is
The total number of electron that takes part in forming bonds in ${N_2}$ is