The reaction $C_6H_6 \rightarrow C_6H_5CH_3$ is known as:

The order of reactivity of the following compounds towards electrophilic substitution will be - [where $\phi = C_6H_5$]:
$I. \phi-CH_3$
$II. \phi-CH_2-CH_3$
$III. \phi-CH(CH_3)_2$
$IV. \phi-C(CH_3)_3$

Which of the following compounds has two different $C-C$ bond lengths?

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:

The product $(A)$ is:

Which of the following compounds does not undergo the Friedel-Crafts reaction?