Nitrogen exists as a diatomic molecule and phosphorus as P₄ because on moving 

1.	up a group, the tendency to form pπ−pπ bonds decreases.
2.	down a group, the tendency to form pπ−pπ bonds decreases.
3.	down a group, the tendency to form dπ−dπ bonds decreases.
4.	up a group, the tendency to form dπ−dπ bonds decreases.

Oxygen forms hydrogen bonds while chlorine does not, because :

The incorrect statement regarding diamond and graphite is-

Boric acid is polymeric due to-

1. Its acidic nature.

2. The presence of hydrogen bonds.

3. Its monobasic nature.

4. Its geometry.

Match the compounds of Xe in Column I with the molecular structure in Column II.

The condition that does not exist in the Haber process for the manufacturing of ammonia is:

1. Pressure (around 200 ×10⁵ Pa)
2. Temperature (700 K)
3. Catalyst such as iron oxide.
4. Presence of inert gases.

The disproportionation reaction of ${\mathrm{H}}_3{\mathrm{PO}}_3$ is as follows:

${\mathrm{H}}_3{\mathrm{PO}}_3$ $\stackrel{∆}{\to }$ $\mathrm{X}$ $+$ $\mathrm{Y}$

 X and Y in the above reaction are:

1. H₃PO₂, HPO₂  

2. H₃PO₄, PH₃

3. H₂PO₆, PO₃

4. None of the above.

The reason behind carbon showing catenation property but lead does not is:

1. Due to the smaller size of C than that of Pb

2. Due to the smaller size of Pb than that of C

3. Due to the smaller ionization energy of C than that of Pb

4. Due to the inert pair effect