Which species is least likely to act as a nucleophile in a reaction with CH₃CH₂Cl?
CH₃CH₂⁺ is a carbocation (electrophile), not a nucleophile, unlike OH⁻, NH₃, CN⁻, which are electron-rich.
Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Fundamental Concepts - Reaction Mechanism - Fission and Reaction Intermediates