The product formed when acetylene is passed through a red-hot tube is:

What will be the product $(A)$ in the following reaction?
$1,4-\text{dibromocyclohexa-1,4-diene} + 2Na \rightarrow (A)$

Consider the following reactions:
$C_2 H_2 \xrightarrow[500^{\circ}C]{\text{red hot iron tube}} A$
$A \xrightarrow[70^{\circ}C]{\text{conc. } HNO_3, \text{conc. } H_2 SO_4} B$
$B \xrightarrow{LiAlH_4} C_6 H_5-N=N-C_6 H_5$
$A$ and $B$ are:

The bond angle between carbon atoms in a benzene molecule is

Which of the following has the lowest heat of combustion?

Write $H$ückel rule and give a suitable example.