Question

Which among the following is the strongest base?
(A) $ {C_6}{H_5}N{H_2} $
(B) $ p - N{H_2}{C_6}{H_4}N{H_2} $
(C) $ m - N{O_2}{C_6}{H_4}N{H_2} $
(D) $ {C_6}{H_5}C{H_2}N{H_2} $

Answer 1

Hint :Whether the substance is acid or base is determined by the number of hydrogen ions present in that compound. If a substance accepts hydrogen, then it is a base and if it donates hydrogen then it is known to be an acid.

Complete Step By Step Answer:
Also understand the concept of basicity by one more fact that the less the electronegative atom , the less stable will be its lone pair of electrons as they will demand for the hydrogen ions , the more they accept hydrogen ions and therefore have a greater basicity .
Also, one more point to keep in mind is that – Aliphatic amines are more basic than aromatic amines.
 This nature of more basicity of aliphatic amines is due to the fact that - nitrogen atom is attached to the alkyl group which shows the $ + I $ effect i.e. the alkyl group are known as donating groups and they can readily give their electron to nitrogen . Thus, the lone pair of electrons can be taken by nitrogen very easily.
But in the case of aromatic amines, nitrogen is attached to the benzene ring, which is the electron accepting group. Also, electrons in the benzene ring undergoes resonance phenomenon and thus are not available for the nitrogen.
So, from the given options we can see our option D is an aliphatic amine i.e. Benzyl amine. All other options are aromatic amines.
Therefore option D Benzyl amine is the correct answer.

Note :
Also our standard periodic table follows some trends regarding the basicity of elements except a few exceptions. So, if we go down in the periodic table, basicity will decrease as the shells will get bigger and bigger on going down and thus, electrons can readily move out of the shell.