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 given options regarding benzene, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** Benzene is a planar molecule.

- **Explanation:** Benzene (C6H6) has a hexagonal structure where all carbon atoms are sp2 hybridized. Each carbon atom forms three sigma bonds (two with adjacent carbon atoms and one with a hydrogen atom) and has a delocalized pi bond system. The geometry of sp2 hybridization is trigonal planar, which means all carbon atoms and hydrogen atoms lie in the same plane. Therefore, this statement is **correct**.

### Step 2: Analyze the second statement
**Statement:** All the carbon atoms in benzene are sp2 hybridized.

- **Explanation:** Each carbon atom in benzene is involved in three sigma bonds and has no lone pairs, leading to a steric number of 3. This indicates that all carbon atoms are sp2 hybridized. Hence, this statement is also **correct**.

### Step 3: Analyze the third statement
**Statement:** The absence of pure double bonds in benzene accounts for its reluctance to show addition reactions under normal conditions.

- **Explanation:** Benzene does not have pure double bonds due to the delocalization of pi electrons across the molecule, which leads to resonance. This resonance stabilizes benzene and makes it less reactive towards addition reactions, as it would lose its aromatic stability. Therefore, this statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement:** The presence of delocalized pi electrons in benzene makes it less stable than hypothetical cyclohexatriene.

- **Explanation:** The delocalization of pi electrons in benzene actually increases its stability compared to hypothetical cyclohexatriene, which would have localized double bonds. Benzene is more stable because of resonance and aromaticity. Therefore, this statement is **incorrect**.

### Conclusion
The incorrect statement among the options provided is the fourth statement: "The presence of delocalized pi electrons in benzene makes it less stable than hypothetical cyclohexatriene."

### Final Answer
The answer to the question is: **Fourth statement is incorrect.**

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