Which of the following is a hydrocarbon?

How is $2,4,6-$trinitrotoluene widely used?

Which of the following species is used as a reagent in the Friedel-Crafts alkylation reaction?

Aromatisation of $n$-heptane by passing over $(Al_2O_3 + Cr_2O_3)$ catalyst at $773 \ K$ gives:

Arrange the following in increasing order of rate of Nitration:
$(a)$ Benzene
$(b)$ Toluene
$(c)$ Hexadeuterobenzene $(C_6D_6)$
$(d)$ Nitrobenzene
$(e)$ Chlorobenzene

What are the major products obtained in each case when compounds $P, Q,$ and $S$ are nitrated using a mixture of $HNO_3/H_2SO_4$?