Choose the incorrect statement from the following

Options

A. Benzene is planer molecule
B. All the carbon atoms in benzene are sp^2hybridised
C. Absence of pure double bond in benzene accounts for the reluctance of benzene to show addition reactions under normal conditions
D. Presence of delocalised π electrons in benzene makes it less stable than hypothetical cyclohexatriene

Answer

To determine the incorrect statement from the options provided, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Benzene is a planar molecule.
**Analysis:** Benzene consists of six carbon atoms that are sp² hybridized. The sp² hybridization results in a trigonal planar geometry around each carbon atom. Thus, benzene is indeed a planar molecule.
**Conclusion:** This statement is correct.

### Step 2: Analyze the second statement
**Statement:** All carbon atoms in benzene are sp² hybridized.
**Analysis:** In benzene, each carbon atom is bonded to two other carbon atoms and one hydrogen atom, forming a total of three sigma bonds. The remaining p-orbital on each carbon overlaps with adjacent p-orbitals to form a delocalized pi bond system. Therefore, all carbon atoms in benzene are sp² hybridized.
**Conclusion:** This statement is correct.

### Step 3: Analyze the third statement
**Statement:** The absence of pure double bonds in benzene accounts for its reluctance to undergo addition reactions under normal conditions.
**Analysis:** Benzene does not have localized double bonds; instead, it has a delocalized pi electron cloud due to resonance. This delocalization makes benzene less reactive towards addition reactions, as these reactions would disrupt the stable resonance structure.
**Conclusion:** This statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** The presence of delocalized pi electrons in benzene makes it less stable.
**Analysis:** This statement is incorrect. The delocalization of pi electrons in benzene actually increases its stability. The resonance stabilization is a key factor that contributes to the aromatic nature of benzene, making it more stable than hypothetical compounds like cyclohexatriene, which would have localized double bonds.
**Conclusion:** This statement is incorrect.

### Final Conclusion
The incorrect statement is: **"The presence of delocalized pi electrons in benzene makes it less stable."**

---