The decreasing order of stability of ${\mathrm{O}}_2,{\mathrm{O}}_2^{-},{\mathrm{O}}_2^{+}$ $\mathrm{and}$ ${\mathrm{O}}_2^{2-}$is: 

1. $O_2^{+}>O_2>O_2^{-}>O_2^{2-}$

2. $O_2^{2-}>O_2^{-}>O_2>O_2^{+}$

3. $O_2>O_2^{+}>O_2^{2-}>O_2^{-}$

4. $O_2^{-}>O_2^{2-}>O_2^{+}>O_2$

A pair in which both species are not likely to exist is:

Combination of atoms A and B that forms an anti-bonding molecular orbital is :

1. $\frac{{\mathrm{\Psi }}_{\mathrm{A}}^2}{{\mathrm{\Psi }}_{\mathrm{B}}^2}$

2. ${\mathrm{\Psi }}_{\mathrm{A}}^2\times {\mathrm{\Psi }}_{\mathrm{B}}^2$

3. ${\mathrm{\Psi }}_{\mathrm{A}}+{\mathrm{\Psi }}_{\mathrm{B}}$

4. ${\mathrm{\Psi }}_{\mathrm{A}}-{\mathrm{\Psi }}_{\mathrm{B}}$

From the perspective of molecular orbital theory, which statement is false?

1. ${\mathrm{Be}}_2$ is not a stable molecule.

2. ${\mathrm{He}}_2$ is not stable but ${\mathrm{He}}_2^{+}$ is expected to exist.

3. Bond strength of ${\mathrm{N}}_2$ is maximum amongst the homonuclear diatomic molecules belonging to the second period.

4. The order of energies of molecular orbitals in ${\mathrm{N}}_2$ molecule is: 

${\mathrm{\sigma }}_{2\mathrm{s}}<{\mathrm{\sigma }}_{2\mathrm{s}}^{*}<{\mathrm{\sigma }}_{2{\mathrm{p}}_{\mathrm{z}}}<({\mathrm{\pi }}_{2{\mathrm{p}}_{\mathrm{x}}}\approx {\mathrm{\pi }}_{2{\mathrm{p}}_{\mathrm{y}}})$
$<({\mathrm{\pi }}_{2{\mathrm{p}}_{\mathrm{x}}}^{*}\approx {\mathrm{\pi }}_{2{\mathrm{p}}_{\mathrm{y}}}^{*})<{\mathrm{\sigma }}_{2{\mathrm{p}}_{\mathrm{z}}}^{*}$