Answer
64.8k+ views
Hint: (1) Benzene is an aromatic compound.
(2) Benzene is not an alkene because unlike alkenes, benzene does not undergo additional reactions easily.
Complete step-by-step answer: By delocalized pi bond, we mean that the electrons in the pi bond are free to move over more than two nuclei. The molecular formula of benzene is \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{6}}}\] . The structure of benzene is:
![](https://www.vedantu.com/question-sets/81ae960a-1b56-4776-95f0-bb95efcd669b5513849672788023998.png)
Benzene is considered to be a resonance hybrid of the following structures:
![](https://www.vedantu.com/question-sets/ebc9e5b2-2c8b-4736-929d-6a3731fc98b83545189981494816825.png)
Each carbon in a benzene molecule is ${\text{s}}{{\text{p}}^{\text{2}}}$ hybridized. The three ${\text{s}}{{\text{p}}^{\text{2}}}$ hybrid orbitals are utilized in the formation of three sigma bonds which leads to a planar hexagonal structure. Now, one unhybridized 2p orbital is left in each carbon atom. Since there are six carbons in benzene, there will be a total of six partially filled unhybridized 2p orbitals. These forms of 3 pi bonds by sideways overlap. Each of these p orbitals can also simultaneously overlap with other p-orbitals on both sides forming a delocalized pi-electron cloud which lies above and below the plane of the whole ring.
![](https://www.vedantu.com/question-sets/5004a378-f7d1-4a66-a35c-c81b8d927d24355230757743951973.png)
Extra stability is provided to the benzene molecule by this delocalization of pi-electrons. Any factor which tries to eliminate this delocalization will decrease the stability of the benzene molecule. This is why benzene does not undergo addition reactions like alkenes because addition reactions lead to the elimination of the delocalization. Resonance in benzene also supports that all the bond lengths of all the six carbon-carbon bonds are equivalent and intermediate between those of ${\text{C - C}}$ single bonds and ${\text{C = C}}$ double bonds.
On the other hand, cyclohexatriene is a molecule without any resonance or delocalization. So it is not stable and cannot exist.
Thus, benzene is more stable than cyclohexatriene due to delocalization of pi-electrons. So, option (b) is correct.
Note: Delocalization of pi-electrons in a molecule results in the attainment of extra stability by that molecule in comparison to those molecules which lack in delocalization.
(2) Benzene is not an alkene because unlike alkenes, benzene does not undergo additional reactions easily.
Complete step-by-step answer: By delocalized pi bond, we mean that the electrons in the pi bond are free to move over more than two nuclei. The molecular formula of benzene is \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{6}}}\] . The structure of benzene is:
![](https://www.vedantu.com/question-sets/81ae960a-1b56-4776-95f0-bb95efcd669b5513849672788023998.png)
Benzene is considered to be a resonance hybrid of the following structures:
![](https://www.vedantu.com/question-sets/ebc9e5b2-2c8b-4736-929d-6a3731fc98b83545189981494816825.png)
Each carbon in a benzene molecule is ${\text{s}}{{\text{p}}^{\text{2}}}$ hybridized. The three ${\text{s}}{{\text{p}}^{\text{2}}}$ hybrid orbitals are utilized in the formation of three sigma bonds which leads to a planar hexagonal structure. Now, one unhybridized 2p orbital is left in each carbon atom. Since there are six carbons in benzene, there will be a total of six partially filled unhybridized 2p orbitals. These forms of 3 pi bonds by sideways overlap. Each of these p orbitals can also simultaneously overlap with other p-orbitals on both sides forming a delocalized pi-electron cloud which lies above and below the plane of the whole ring.
![](https://www.vedantu.com/question-sets/5004a378-f7d1-4a66-a35c-c81b8d927d24355230757743951973.png)
Extra stability is provided to the benzene molecule by this delocalization of pi-electrons. Any factor which tries to eliminate this delocalization will decrease the stability of the benzene molecule. This is why benzene does not undergo addition reactions like alkenes because addition reactions lead to the elimination of the delocalization. Resonance in benzene also supports that all the bond lengths of all the six carbon-carbon bonds are equivalent and intermediate between those of ${\text{C - C}}$ single bonds and ${\text{C = C}}$ double bonds.
On the other hand, cyclohexatriene is a molecule without any resonance or delocalization. So it is not stable and cannot exist.
Thus, benzene is more stable than cyclohexatriene due to delocalization of pi-electrons. So, option (b) is correct.
Note: Delocalization of pi-electrons in a molecule results in the attainment of extra stability by that molecule in comparison to those molecules which lack in delocalization.
Recently Updated Pages
Write a composition in approximately 450 500 words class 10 english JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Arrange the sentences P Q R between S1 and S5 such class 10 english JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What is the common property of the oxides CONO and class 10 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What happens when dilute hydrochloric acid is added class 10 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
If four points A63B 35C4 2 and Dx3x are given in such class 10 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
The area of square inscribed in a circle of diameter class 10 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Other Pages
A boat takes 2 hours to go 8 km and come back to a class 11 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
In the ground state an element has 13 electrons in class 11 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Differentiate between homogeneous and heterogeneous class 12 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Electric field due to uniformly charged sphere class 12 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
According to classical free electron theory A There class 11 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Excluding stoppages the speed of a bus is 54 kmph and class 11 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)