The product formed when benzene is nitrated by fuming nitric acid is

In the Friedel-Crafts reaction,toluene can be prepared by using:

The electrophile $NO_2^+$ reacts with which of the following compounds? In which case will $NO_2^+$ attack at the meta position?
$(I)$ $C_6H_5-CCl_3$
$(II)$ $C_6H_5-NO_2$
$(III)$ $C_6H_5-CHO$
$(IV)$ $C_6H_5-O^-$

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

In the following reactions,$X$ and $Y$,respectively,are

The presence of a nitro group in a benzene ring......