Question

$N_2$ and $O_2$ are converted into monocations, $N_2^{+}$ and $O_2^{+}$ respectively. Which of the following is wrong ?

• A. In $N_2^{+}$, N - N bond weakens
• B. In $O_2^{+}$, the O-O bond order increases
• C. In $O_2^{+}$, paramagnetism decreases
• D. $N_2^{+}$ becomes diamagnetic.

Answer 1

The correct option is D

$N_2^{+}$ becomes diamagnetic.

B.O. = $\frac{No.ofanti-bondingelectrons-No.ofbondingelectrons}{2}$

B.O. in $N_2=(10–4)/2=3$

B.O. in $N_2^{+}=(9–4)/2=2.5$

B.O. in $O_2=(10–6)/2=2.0$

B.O. in $O_2^{+}=(10-5)/2=2.5$

Paramagnetism depends on the number of unpaired electrons. Compared to the MOT of $O_2$, the MOT of $O_2^{+}$ has one less unpaired electron and thus the latter is less paramagnetic than the dioxygen molecule. $N_2^{+}$ contains one unpaired electron and hence is paramagnetic. Therefore option (d) is wrong . All other statements are correct.