Friedel-Crafts reaction using $MeCl$ and anhydrous $AlCl_3$ will take place most efficiently with

Out of benzene,$m$-dinitrobenzene and toluene,which will undergo nitration most easily and why?

What is the decreasing order of reactivity amongst the following compounds towards aromatic electrophilic substitution?
$I.$ Chlorobenzene
$II.$ Benzene
$III.$ Anilinium chloride
$IV.$ Toluene

The major product formed in the following reaction sequence is:
$C_6H_5-CHBr-CH_2Br$ $\xrightarrow[(ii) NaNH_2]{(i) alc. KOH}$ $\xrightarrow[(iii) \text{Red hot iron tube}, 873 K]{}$

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

Benzene on nitration gives nitrobenzene in the presence of a mixture of $HNO_3$ and $H_2SO_4$,where: