Some of the properties of the two species, $N{O}_3^{-}$ $and$ $H_3{O}^{+}$  are described below. Which one of them is correct?
 

1.	Isostructural with the same hybridization for the central atom.
2.	Isostructural with different hybridization for the central atom.
3.	Similar in hybridization for the central atom with different structures.
4.	Dissimilar in hybridization for the central atom with different structures.

In which of the following molecules the central atom does not have sp³ hybridization?

1. SF₄

2. $B{F}_4^{-}$

3. $N{H}_4^{+}$

4. CH₄

The most preferred structure among the following with the lowest energy for SO₃ is: 

1.		2.
3.		4.

The pairs of species of oxygen and their magnetic behaviours are given below. Which of the following represents the correct description?

1. $\mathrm{O},$ ${\mathrm{O}}_2^{2-}$ - Both paramagnetic
2. ${\mathrm{O}}_2^{-},$ ${\mathrm{O}}_2^{2-}$ - Both diamagnetic
3. ${\mathrm{O}}^{+},$ ${\mathrm{O}}_2^{2-}$ - Both paramagnetic
4. ${\mathrm{O}}_2^{+},$ ${\mathrm{O}}_2$ - Both paramagnetic

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⁺  

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.  $\pi *$ $orbital$ $$