The decreasing order of strength of the bases, `OH^(-), NH_(2)^(-), H-C-=C^(-)` and `CH_(3)-CH_(2)^(-)`:

Options

A. `CH_(3) -CH_(2)^(-) gt NH_(2)^(-) gt H-C -= C^(-) gt OH^(-)`
B. `H-C -= C^(-) gt CH_(3) -CH_(2)^(-) gt NH_(2)^(-) gt OH^(-)`
C. `OH^(-) gt NH_(2)^(-) gt H-C -= C^(-) gt CH_(3) -CH_(2)^(-)`
D. `NH_(2)^(-) gt H -C -= C^(-) gt OH^(-) gt CH_(3) -CH_(2)^(-)`

Answer

B

Explanation

the conjugate acids of the bases `OH^(-),NH_(2)^(-), H-C-=C^(-) " and "CH_(3)-CH_(2)^(-)` are respectively `H-OH, NH_(3)^(2), H-C-=CH " and " CH_(3)CH_(3).` Their acidic nature is in the order :
`HOH gt HC-=CH gt NH_(3) gt CH_(3)-CH_(3)`
Now a strong acid has weak conjugate base. Thus the strength of the bases is in the order
`CH_(3)-CH_(2)^(-) gt HC -=C^(-) gt OH^(-)`