How many delocalised $\pi $-electrons are there in the following compound ?
A. 1 B. 2 C. 4 D. 6
Hint: A pair of electrons which do not make any bond are known as lone pairs whereas a pair of electrons, which is found in the paired condition they are known as electron pairs. Lone pairs electrons can move in the lattice structure.
Complete step by step answer: - The delocalised electrons are those electrons which can move from one bond to the other in a molecule structure. - The structure which is given in the question is of pyrroles, a 5-membered ring. - In the given, we have to tell about the delocalised electron but they should belong to $\pi $- electrons. - $\pi $-electrons are those electrons which are formed when a double-bond is formed i.e. they are found in the double-bond. - So, as we can see that there are a total of two double bonds so there are 4 $\pi $-electrons. - Along with it, two delocalised $\pi $-electrons are also present above the nitrogen atom. - So, a total of 6 delocalised $\pi $- electrons are present in the pyrrole. - These delocalised electrons are also responsible for the electrical conduction due to their movement in the lattice structure. Therefore, option D. is the correct answer.
Note: $\pi $-electrons are found in the double bond whereas $\sigma $- electrons are found in the single bond. Usually without the formation of sigma bond the formation of $\pi $bond can not take place. Moreover, benzene is another example of the delocalised $\pi $-electron due to which the benzene has a stable structure.
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