Answer the question on the basis of passage given below:

Second period elements of p-Block differ from the rest of their group members due to their small atomic size, high electronegativity, high ionization enthalpy and absence of d-orbitals.

The elements from the second period like C, N, O have unique property of forming pa pa multiple bonds whereas other heavier elements of p-block form da pa multiple bonds. This changes the properties of second period elements to great extent. Also the single bond strength of the p-block elements with their own atoms gets affected by their atomic size and presence of lone pairs.

Inert pair effect also affects the properties of the p-Block elements especially for those elements which are present from 4th period onward and this happens due to poor screening effect of inner (n-1) d subshell electrons.

\(N_2\) is a gas where in \(P_4\) is a solid, because-

Nitrogen can form \(p\pi \) - \(p\pi \) bond while phosphorus cannot do so.

The correct answer is option 2. Nitrogen can form \(p\pi \) - \(p\pi \) bond while phosphorus cannot do so.

Let us delve into the option in more detail:

1. Nitrogen's Ability to Form \(p\pi \) - \(p\pi \) Bonds: Nitrogen atoms have three unpaired electrons in their \(2p\) orbitals. When two nitrogen atoms come together to form a nitrogen molecule (\(N_2\)), these unpaired electrons can overlap to form \(p\pi \) - \(p\pi \) bonds. This type of bond arises from the sideways overlap of two \(p\) orbitals, allowing for efficient sharing of electrons. The presence of \(p\pi \) - \(p\pi \) bonds contributes significantly to the stability of the nitrogen molecule.

2. Phosphorus's Limited Ability to Form Such Bonds: Phosphorus also has \(p\) orbitals, but they are larger in size compared to nitrogen due to phosphorus's larger atomic size. While phosphorus can form \(p\) bonds, the extent to which it can form \(p\pi \) - \(p\pi \) bonds is limited compared to nitrogen. This is partly due to the larger size of phosphorus's \(p\) orbitals, which results in less effective overlap between them compared to nitrogen. As a result, the bonding between phosphorus atoms in a phosphorus molecule (\(P_4\)) is weaker than the bonding between nitrogen atoms in a nitrogen molecule.

3. Effect on Intermolecular Forces: In the solid state, molecules are held together by intermolecular forces. In the case of \(N_2\), the presence of strong \(p\pi \) - \(p\pi \) bonds leads to relatively weak intermolecular forces between nitrogen molecules. These weak forces allow \(N_2\) molecules to move freely and hence exist as a gas at room temperature and pressure.

In contrast, the weaker \(p\) bonding in \(P_4\) results in stronger intermolecular forces between phosphorus molecules. These stronger forces require more energy to overcome, thus keeping \(P_4\) molecules closely packed together in the solid state at room temperature and pressure.

So, the ability of nitrogen to form strong \(p\pi \) - \(p\pi \) bonds compared to phosphorus is a key factor contributing to the difference in physical states between \(N_2\) (gas) and \(P_4\) (solid).