Benzene was discovered by

The compound shown below can be readily prepared by Friedel-Crafts reaction between

What is the major product of the following reaction?
$1,4-dichlorocyclohexa-1,4-diene \xrightarrow{Na, \text{dry ether}} ?$

In the reaction,
$X$ and $Y$ respectively are :-

The number of benzene derivatives of the formula $C_7H_8O$ is :

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : Benzene is more stable than hypothetical cyclohexatriene.
Reason $R$ : The delocalized $\pi$ electron cloud is attracted more strongly by nuclei of carbon atoms.
In the light of the above statements,choose the correct answer from the options given below: