JEE Main · 2025 · 29 Jan 2025 · Shift 1 · General Organic Chemistry

A nucleophile has an available electron pair (or π electrons) to donate to an electrophilic centre. Checking each species: ${\mathrm{NH}}_3$ (lone pair on N), $\mathrm{PhSH}$ (lone pair on S), $({\mathrm{H}}_3\mathrm{C}{)}_2\mathrm{S}$ (lone pair on S), ${\mathrm{H}}_2\mathrm{C}={\mathrm{CH}}_2$ (π electrons available to attack an electrophile) and ${}^{\ominus }\mathrm{OH}$ (negatively charged, strongly nucleophilic) are all nucleophiles.

${\mathrm{H}}_3{\mathrm{O}}^{\oplus }$ is electron-deficient and behaves as an acid/electrophile, not a nucleophile, while the carbonyl carbon in $({\mathrm{CH}}_3{)}_2\mathrm{CO}$ and the imine carbon in $>={\mathrm{NCH}}_3$ are themselves electrophilic sites rather than nucleophilic ones.

Counting the qualifying species gives 5 nucleophiles.