What is the number of $\pi$ electrons present in pyridine?

The reaction of benzene with $CH_3COCl$ in the presence of $AlCl_3$ yields ...........

Identify the correct method for the synthesis of the compound shown below from the following alternatives.

Which of the following is a heterocyclic aromatic compound?

Which one of the following gives a sooty flame on combustion?

What is the ratio of glyoxal to pyrualdehyde obtained in the ozonolysis of $o-xylene$ as shown in the reaction below?
$o-Xylene$ $\xrightarrow[{(2) Zn}]{{(1) O_3}} CHO-CHO \text{ (Glyoxal)} + CH_3CO-COCH_3 \text{ (2,3-Butanedione)} + CH_3CO-CHO \text{ (Pyrualdehyde)}$