Arrange the following in the correct order of reactivity towards nucleophilic substitution reaction.

I. 1-chloro-2-nitrobenzene

II. Chlorobenzene

III. 1-chloro-3-nitrobenzene

Reactions that produce $n$-butanol in the following are :

I. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}=\mathrm{CH}_2 \xrightarrow[\text { (ii) } \mathrm{NaOH} / \mathrm{H}_2 \mathrm{O}_2]{\text { (i) } \mathrm{B}_2 \mathrm{H}_6}$

II. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO} \xrightarrow[\text { (ii) } \mathrm{H}_2 \mathrm{O}]{\text { (i) } \mathrm{CH}_3 \mathrm{Mgl}}$

III. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CN} \xrightarrow[\substack{\text { (ii) } \mathrm{H}_3 \mathrm{O} \\ \text { (iii) } \mathrm{NaBH}_4}]{\text { (i) } \mathrm{SnCl}_2, \mathrm{HCl}}$

IV. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CO}_2 \mathrm{H} \xrightarrow{\mathrm{B}_2 \mathrm{H}_6}$

$$ \text { What are } X \text { and } Y \text { in the following reaction sequence? } $$

$$ \text { Predict } A \text { and } B \text { in the following reaction sequence : } $$

$$ \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{COOH} $$

$$ \xrightarrow[\text { Red phosphorus }]{\mathrm{Br}_2} A \xrightarrow{\mathrm{KOH} \text { (alc.) }} B$$