A paramagnetic molecule among the following is:

Which of the following is a paramagnetic compound?

1. ${\mathrm{N}}_2$

2. ${\mathrm{H}}_2$

3. ${\mathrm{Li}}_2$

4. ${\mathrm{O}}_2$

What is the correct sequence of bond order for the specified species?

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