In the following reaction,the catalyst used is:

The correct structure of benzene was proposed by

Which of the following benzene ring substituents is deactivating but ortho-para directing?

Hexane $\xrightarrow[\substack{773 \ K \\ 10-20 \ atm}]{Cr_2O_3} X$ $\xrightarrow[\text{Anhydrous } AlCl_3]{CH_3COCl} Y$. $Y$ in the above sequence of reactions is

The function of $AlCl_3$ in Friedel-Crafts reaction is

Which of the following compounds is most reactive toward electrophilic substitution reaction?