Chemistry - GOC Question with Solution | TestHub

Here electrophile generation is possible in reactions I, II and IV as follows
$\left(\mathrm{I}\right)$
$\left(\mathrm{I}\mathrm{I}\right)$$\mathrm{C}{\mathrm{H}}_3–\mathrm{C}\mathrm{H}=\mathrm{C}{\mathrm{H}}_2+\stackrel{\oplus }{\mathrm{H}}\to \mathrm{C}{\mathrm{H}}_3–\stackrel{\oplus }{\mathrm{C}}\mathrm{H}–\mathrm{C}{\mathrm{H}}_3$
$\left(\mathrm{I}\mathrm{I}\mathrm{I}\right)$${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}+{\mathrm{H}}_3\stackrel{\oplus }{\mathrm{O}}\to \mathrm{n}\mathrm{o}\hspace{0.33em}\text{reaction}$
$\left(\text{IV}\right){\text{HNO}}_{\text{3}}\text{+}{\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\to \stackrel{\oplus }{{\text{NO}}_{\text{2}}}\text{+}{\text{H}}_{\text{3}}\stackrel{\oplus }{\text{O}}\text{+}{\text{H}}_{}{\text{SO}}_{\text{4}}^{-}$