A molecule that has a complete octet is:

 1. BeCl₂(dimer)       

 2. BeH₂(dimer)

 3. BeH₂(s)               

 4. BeCl₂(s)

In ${\mathrm{PO}}_4^{3-}$ ion, the formal charge on the oxygen atom of the P-O bond is :

An electron-deficient compound among the following is:

Which of the following species deviates from the octet rule?

1. $C{O}_3^{2-}$

2. $H_{2}S{O}_3$

3. $PC{l}_3$

4. $O_3$

The set of oxides of nitrogen that are paramagnetic in nature is:

1. NO, N₂O

2. N₂O₃, NO

3. NO, NO₂

4. N₂O, NO₂

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

1.		2.
3.		4.

Consider the following five chemical species:

NH₃, AlCl₃, BeCl₂, CCl₄ and PCl₅

How many of these species violate the octet rule by having either fewer or more than
eight electrons in the valence shell of their central atom?

Which of the following pair of elements can form an ionic compound?

 When two atoms combine to form a molecule, energy is: