Animated Solution for Chemistry - s and p-Block Elements: Which of the following is wrong statement?

Welcome to a classic JEE problem that is less of a single question and more of a comprehensive test of your p-block knowledge!

In this problem, we are asked to identify the wrong statement among four given options. This means we have to put on our detective hats and investigate each statement individually.

Let's break them down one by one and see if we can catch any factual errors.

The Isoelectronic Check

The first statement claims that $\text{ONCl}$ and ${\text{ONO}}^{-}$ are not isoelectronic.

To verify this, we need to understand what "isoelectronic" means. Isoelectronic species are atoms, molecules, or ions that have the exact same total number of electrons.

Let's calculate the total electrons for the $\text{ONCl}$ molecule. Oxygen contributes $8$ electrons, Nitrogen contributes $7$, and Chlorine contributes $17$.

Now, let's look at the nitrite ion, ${\text{ONO}}^{-}$. We have two Oxygen atoms ($8\times 2=16$), one Nitrogen atom ($7$), and one extra electron due to the negative charge.

Comparing the two, $32$ is clearly not equal to $24$. Therefore, they are indeed not isoelectronic. Statement (a) is factually correct!

The Geometry of Ozone

Next, we evaluate the claim that the ozone (${\text{O}}_3$) molecule is bent.

To determine the shape, we must draw the Lewis structure of ozone and apply VSEPR theory. In ${\text{O}}_3$, the central Oxygen atom forms a double bond with one Oxygen and a single coordinate bond with the other.

Crucially, the central Oxygen also possesses one lone pair of electrons. We calculate the Steric Number by adding the number of sigma bonds (bond pairs) and lone pairs.

A steric number of $3$ corresponds to $s{p}^2$ hybridization, which normally has a trigonal planar electron geometry.

However, the presence of the lone pair exerts a strong repulsive force on the bond pairs, pushing them closer together. This distortion results in a bent or V-shaped molecular geometry. Thus, statement (b) is also correct!

The Colors of Ozone

Statement (c) states that ozone is violet-black in the solid state.

This is a direct factual property from the chemistry of Group 16 elements. Ozone exhibits fascinating color changes depending on its physical state.

At room temperature, it is a pale blue gas. When condensed into a liquid, it turns dark blue.

Finally, when frozen into a solid, it forms a striking violet-black solid. Therefore, statement (c) is perfectly accurate.

The Magnetic Nature of Ozone

The final statement claims that ozone is a diamagnetic gas.

Magnetic properties are determined by the presence or absence of unpaired electrons. Let's count the total valence electrons in the ${\text{O}}_3$ molecule.

Each Oxygen atom has $6$ valence electrons, and since there are three atoms, we have:

Because $18$ is an even number, all the electrons in the molecular orbitals of ozone are completely paired up.

Species with zero unpaired electrons are repelled by magnetic fields and are classified as diamagnetic. Statement (d) is absolutely correct!

A Plot Twist!

We have meticulously analyzed all four statements, and every single one of them turned out to be factually correct.

But wait, the question asked us to find the wrong statement! What does this mean?

This means the question itself is flawed. In the actual JEE Main 2013 exam, this was considered a bonus question, and all students were awarded full marks for it.

While it might feel anti-climactic not to find a "wrong" option, the true victory lies in the rigorous conceptual revision we just performed. Keep trusting your concepts!