Animated Solution for Chemistry - s and p-Block Elements: The correct statement with respect to dinitrogen is

Exploring the Properties of Dinitrogen

When we take a deep breath, we are inhaling a mixture of gases, but the vast majority of it—about 78%—is dinitrogen ($N_2$). Despite being so abundant, nitrogen is famously unreactive under normal conditions. Let's dive into the molecular structure of $N_2$ to understand why it behaves the way it does and evaluate the given statements.

Is nitrogen gas attracted to a magnet? To answer this, we must look at its electronic structure through the lens of Molecular Orbital Theory. A single nitrogen atom has 7 electrons, so a dinitrogen molecule ($N_2$) has a total of 14 electrons.

When we fill these 14 electrons into the molecular orbitals, the configuration is: $\sigma 1s^2,{\sigma }^{\ast }1s^2,\sigma 2s^2,{\sigma }^{\ast }2s^2,\pi 2p_x^2=\pi 2p_y^2,\sigma 2p_z^2$

Notice that every single electron is paired up. Because there are zero unpaired electrons, dinitrogen is strictly diamagnetic. It will be slightly repelled by a magnetic field, not attracted to it. Therefore, the statement claiming it is paramagnetic is incorrect.

Our atmosphere is a giant mixture of $N_2$ and $O_2$. If these two gases reacted easily at room temperature ($25^{\circ }\text{C}$), our air would be filled with toxic nitrogen oxides!

The two nitrogen atoms in $N_2$ are held together by a formidable triple bond ($N\equiv N$). This bond has an exceptionally high bond dissociation enthalpy of $941.4{\text{ kJ mol}}^{-1}$. To force nitrogen to react with oxygen, you need to supply a massive amount of energy—typically temperatures exceeding $2000^{\circ }\text{C}$, like those found in lightning strikes or internal combustion engines.

Thus, $N_2$ definitely does not combine with dioxygen at $25^{\circ }\text{C}$.

If you cool nitrogen gas down to $77.2\text{ K}$ ($-196^{\circ }\text{C}$), it condenses into a liquid. Liquid nitrogen is a staple in laboratories and hospitals. Because it is so intensely cold, it is widely used as a cryogen in cryosurgery to rapidly freeze and destroy abnormal or diseased tissues, such as warts or precancerous skin lesions. The statement claiming it is not used in cryosurgery is factually wrong.

Finally, we return to that incredibly strong triple bond. Because it takes so much energy to break the $N\equiv N$ bond, nitrogen gas is highly unreactive, or inert, at room temperature.

Chemists take advantage of this property all the time. When working with highly reactive chemicals that might spontaneously combust or degrade in the presence of oxygen or moisture, chemists flush their reaction vessels with nitrogen gas. It acts as a perfect inert diluent, providing a safe, unreactive blanket for sensitive chemistry to take place.

Therefore, the statement that dinitrogen can be used as an inert diluent for reactive chemicals is absolutely correct!