Amines — Chemistry STD 12 Science — Question

1. In CH₃NH₂, the +I effect of -CH₃ group makes lone pair of electrons on N-atom more available for donation. On the other hand in C₆H₅NH₂, the resonance effect causes delocalisation of lone pair of electrons over benzene ring and makes it less available for donation.

Hence, CH₃NH₂ is more basic than C₆H₅NH₂.

2. CH₃NH₂ is more basic than NH₃. CH₃ group due to its +ve I effect pushes electron towards nitrogen in $\text{CH}_3\stackrel{{..\ \ \ \ \ \ \ }}{\hbox{N}\text{H}_2}$ and this makes the unshared electron pair more available for sharing with the proton of the acid.
3.  

is stronger base than

as CH₃ group is electron releasing by +I effect and hyperconjugation effect.