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.

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

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