Given below are four compounds:
$(a)$ $n$-propyl chloride,
$(b)$ $iso$-propyl chloride,
$(c)$ $sec$-butyl chloride,
$(d)$ $neo$-pentyl chloride.
Percentage of carbon in the one which exhibits optical isomerism is:

Which of the following cannot undergo nucleophilic substitution under ordinary conditions?

Write the structure of the major organic product in each of the following reactions:
$(i)$ $CH_3-CH_2-CH_2-Cl + NaI \xrightarrow[\text{heat}]{\text{acetone}}$
$(ii)$ $CH_3-C(CH_3)_2-Br + KOH \xrightarrow[\text{heat}]{\text{ethanol}}$
$(iii)$ $CH_3-CH(Br)-CH_2-CH_3 + NaOH \xrightarrow{\text{water}}$
$(iv)$ $CH_3-CH_2-Br + KCN \xrightarrow{\text{aq. ethanol}}$
$(v)$ $C_6H_5-ONa + C_2H_5-Cl \longrightarrow$
$(vi)$ $CH_3-CH_2-CH_2-OH + SOCl_2 \longrightarrow$
$(vii)$ $CH_3-CH_2-CH=CH_2 + HBr \xrightarrow{\text{peroxide}}$
$(viii)$ $CH_3-CH=C(CH_3)_2 + HBr \longrightarrow$

Match the reactions in List-$I$ with the major products in List-$II$:
| List-$I$ | List-$II$ (Major Product) |
| :--- | :--- |
| $(A)$ $CH_3-CHBr-CH_2Br \xrightarrow{KOH/C_2H_5OH}$ | $(I)$ $1^{\circ}$-alkyl bromide |
| $(B)$ $CH_3-CH_2-CH=CH_2 \xrightarrow{HBr, (C_6H_5CO)_2O_2, \Delta}$ | $(II)$ $2^{\circ}$-alkyl bromide |
| $(C)$ $CH_3CH_2CH_3 \xrightarrow{Br_2, h\nu}$ | $(III)$ Allyl bromide |
| $(D)$ $CH_3-CH=CH_2 \xrightarrow{NBS, \Delta}$ | $(IV)$ Alkenyl bromide |

Explain two differences between haloalkanes and haloarenes.

Identify the correct order of reactivity for the following pairs towards the respective mechanism:
$(A)$ $S_{N}2$: Isobutyl bromide > tert-Butyl bromide
$(B)$ $S_{N}1$: Benzyl bromide > $2-$Phenylethyl bromide
$(C)$ Electrophilic substitution: Chlorobenzene > $1-$Chloro$-4-$nitrobenzene
$(D)$ Nucleophilic substitution: Bromobenzene < $1-$Bromo$-4-$nitrobenzene
Choose the correct answer from the options given below: