The compound obtained by passing $C_2H_2$ through a red-hot tube is ...........

For the electrophilic aromatic substitution reaction on the benzene ring,the substituents are $-CH_3$,$-CH_2Cl$,$-CHCl_2$,and $-CCl_3$. What is the increasing order of reactivity towards electrophilic substitution?

Which of the following is most reactive towards electrophilic nitration?

Which of the following ring compounds obeys Huckel's rule?

Give reason: Nitration of benzene is not possible with only $HNO_3$.

What is the product obtained from the reductive ozonolysis of benzene?