Which one of the following species does not exist?

1. ${\mathrm{Be}}_2^{+}$

2. Be₂

3. B₂

4. N₂

Which one of the following is not paramagnetic ?

1. NO

2. ${\mathrm{N}}_2^{+}$

3. CO

4. ${\mathrm{O}}_2^{-}$

According to molecular orbital theory, arrange the nitrogen species in each list in ascending order of bond order:

1. ${\mathrm{N}}_2^{-} < {\mathrm{N}}_2 < {\mathrm{N}}_2^{2-}$

2. ${\mathrm{N}}_2^{2-} < {\mathrm{N}}_2^{-} < {\mathrm{N}}_2$

3. ${\mathrm{N}}_2 < {\mathrm{N}}_2^{2-} <\hspace{0.17em}{\mathrm{N}}_2^{-}$

4. ${\mathrm{N}}_2^{-} < {\mathrm{N}}_2^{2-} < {\mathrm{N}}_2$

Which of the following statement is not correct from the view point of molecular orbital theory ?

1. Be₂ is not a stable molecule

2. He₂ is not a stable but He_2⁺ is expected to exist.

3. Bond strength of N₂ is maximum amongst the homonuclear diatomic molecules belonging to the second period.

4. The order of energies of molecular orbitals in N₂ molecule is

 s2s < s*2s < s2p_z < (p2p_x=p2p_y) < (p*2p_x=p*2p_y) < s*2p_z  

Which molecules/ions are most paramagnetic?

1. B₂

2. C₂

3. ${\mathrm{O}}_2^{+}$

4. ${\mathrm{O}}_2^{-}$

Which has highest bond energy ?

1. CO

2. CO⁺

3. N₂

4. ${\mathrm{N}}_2^{+}$

Which of the following has largest bond angle.

1. H₂O

2. F₂O

3. Cl₂O

4. H₂S

In the molecular orbital diagram for ${\mathrm{O}}_2^{+}$ ion. the HOMO is :-

(1) $\sigma$ MO orbital

(2) π MO orbital

(3)  π^* MO orbital

(4) $\stackrel{*}{\sigma }$ MO orbital

${\mathrm{N}}_2$ and ${\mathrm{O}}_2$ are converted to monocations ${\mathrm{N}}_2^{+}$ and ${\mathrm{O}}_2^{+}$ respectively. Which of the following is incorrect?

1. In ${\mathrm{N}}_2^{+}$, the $\mathrm{N}-\mathrm{N}$ bond weakens.

2. In ${\mathrm{O}}_2^{+}$, the $\mathrm{O}-\mathrm{O}$ bond order increases.

3. In ${\mathrm{O}}_2^{+}$, the paramagnetism decreases.

4. ${\mathrm{N}}_2^{+}$ becomes diamagnetic.

Which one of the following pairs of species have the same bond order?

(1) CO, NO

(2) O_2-  , CN-

(3) CN- , NO+

(4) N+ , CN+