Considering the basic strength of amines in an aqueous solution, which one has the smallest pK b value?

Step-by-step solution

Since in aromatic amines the lone pair undergoes delocalisation, aliphatic amines are more basic than aromatic amines. Ph - NH 2 < R - NH 2 In an aliphatic amine, due to the + I effect of - CH 3 the order will be 3 ° > 2 ° > 1 ° . In an aqueous solution, H - bonding takes place. So, the order will be 1 ° > 2 ° > 3 ° . However, the resultant basic order is due to a mixture of both the effects( + I and hydrogen bond). So, the order is 2 ° > 3 ° > 1 &