Which of the following amines can act as a nucleophile in an S_N₂ reaction with CH₃CH₂Br ?
Methylamine ( CH₃NH₂ ) has a lone pair on nitrogen, enabling it to act as a nucleophile in an S_N₂ reaction with CH₃CH₂Br to form CH₃NHCH₂CH₃, a property noted in the PDF.
Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Chemical Bonding, Topic: Hybridization of nitrogen in CH₃NH₂, sp³ hybridization, pyramidal geometry.