Nucleophiles donate electron pairs

Steps:

• Recall that nucleophiles are species that donate electrons in chemical reactions.
• Examine each choice against the core definition of a nucleophile.
• Identify that donating a lone pair is the universal trait.
• Eliminate options that describe only specific cases or unrelated features.

Why B is correct:

• By definition, a nucleophile (nucleus-loving) attacks electron-deficient centers by donating a lone pair of electrons, as in SN2 reactions where Nu: → C.

Why the others are wrong:

• A: Nucleophiles target electrophilic centers, not necessarily double bonds (e.g., in SN1 reactions).
• C: Nucleophiles can be molecules like NH3, not just single atoms.
• D: Neutral nucleophiles like water exist and donate lone pairs without a charge.

Final answer: B