Which of the following is a free radical substitution reaction?

For the electrophilic substitution reaction involving nitration,which of the following sequences regarding the rate of reaction is true?

Which of the following is a carcinogen?

Identify the main product of the reaction between benzene and $1$-chloropropane in the presence of $AlCl_3$.

In the reaction of benzene with an electrophile $E^{+}$,the structure of the intermediate $\sigma$-complex can be represented as

The reaction$(s)$ leading to the formation of $1,3,5-$trimethylbenzene is (are):
$(A)$ $3CH_3COCH_3 \xrightarrow{Conc. H_2SO_4, \Delta} 1,3,5-\text{trimethylbenzene}$
$(B)$ $3CH_3C \equiv CH \xrightarrow{\text{heated iron tube}, 873 K} 1,3,5-\text{trimethylbenzene}$
$(C)$ $1,3,5-\text{triacetylbenzene} \xrightarrow{1) Br_2, NaOH, 2) H_3O^+, 3) \text{sodalime}, \Delta} \text{benzene}$
$(D)$ $1,3,5-\text{triformylbenzene} \xrightarrow{Zn/Hg, HCl} 1,3,5-\text{trimethylbenzene}$