Considering the basic strength of amines in aqueous sloution which one has the smallest `pk_(b)` value .

Options

A. `(CH_(3))_(3)N`
B. `C_(6)H_(5)NH_(2)` and `HCOOH` respectively
C. `(CH_(3))_(2)NH`
D. `CH_(3)NH_(2)`

Answer

C

Explanation

Basicity order :
`(CH_(3))_(2)NHgtCH_(3)NH_(2)gt(CH_(3))_(3)NgtC_(6)H_(5)NH_(2)` (in aq medium)
`pK_(b)` order :
`(CH_(3))_(2)NHltCH_(3)NH_(2)lt(CH_(3))_(3)NltC_(6)H_(5)NH_(2)`
smallest `pK_(b): (CH_(3))_(2)NH`