Which from following amines has lowest pK _ b value?

Step-by-step solution

Identifying the amine with the lowest pK _ b reveals the strongest base among the given options. Ethylamine ( C ₂ H ₅ NH ₂ ) is a primary aliphatic amine where the ethyl group donates electrons via the +I effect, enhancing nitrogen's electron density and basicity; pK _ b 3.25 . Trimethylamine ( ( CH ₃)₃ N ) is a tertiary aliphatic amine with significant +I effects, but steric hindrance reduces solvation of its conjugate acid, lowering basicity; pK _ b 4.20 . Aniline ( C ₆ H ₅ NH ₂ ) is an aromatic amine with resona