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. $O_2^{-}>O_2^{2-}>O_2^{+}>O_2$

The correct order of bond order in the following species is:

A paramagnetic molecule among the following is:

The bond order of 1.5 is shown by:  

The pair of species with the same bond order is:

1. $O_2^{2-},$ $B_2$

2. $O_2^{+},\mathrm{ N}{O}^{+}$

3. NO, CO

4. $N_2,O_2$

During change of $O_2$ to $O_2^{-}$ ion, the electron adds on which one of the following orbitals? 

1.  $\pi$ $orbital$ $$

2.  $\sigma *$ $orbital$ $$

3.  $\sigma$ $orbital$

4.  $\pi *$ $orbital$ $$

Four diatomic species are listed below. Identify the correct order in which the bond order is increasing in them.

1. O₂^- < NO < C₂^2- < He₂⁺  
$$2. C₂^2- < He₂⁺ < O₂^- < NO  
$$3. He₂⁺ < O₂^- < NO < C₂^2-
4. NO < O₂^- < C₂^2- < He₂⁺