Number of $\pi$ electrons present in naphthalene is :

$A$ $C_8H_{10}$ hydrocarbon is nitrated by $HNO_3$ and sulphuric acid. Two,and only two,$C_8H_9NO_2$ isomers are obtained. Which of the following fits this evidence?

Nitrobenzene can be prepared from benzene by using a mixture of conc. $HNO_3$ and conc. $H_2SO_4$. In the nitrating mixture,$HNO_3$ acts as a

Which of the following is a Friedel-Crafts reaction?

Which order is correct for the decreasing reactivity to ring monobromination of the following compounds: $C_6H_5CH_3$ $(I)$,$C_6H_5COOH$ $(II)$,$C_6H_6$ $(III)$,and $C_6H_5NO_2$ $(IV)$?

The step shown below is a recent synthesis of corannulene. Product $A$ is