Question

Arrange the following in decreasing order of basic character.
I..p-toluidine
II.N, N-dimethyl-p-toluidine
III.p-nitroaniline
IV.Aniline
II > III > I > IV
I > II > III > IV
II > I > IV > III
IV > III > I > II

Answer 1

Hint: In the given question the basic character of some compounds has been discussed. The basic character of the compound denotes their basicity. It depends on the nature of the compound and also on the reagents used.

Complete Step by step answer: In p-toluidine there are two methyl group on N which shows whereas hyper conjugation and inductive effect of methyl group at para position makes the compound N, N−dimethyl−p−toluidine more basic.
In para toluidine the inductive effect and hyperconjugation of one methyl group takes place at para position which makes it less basic than N, N-dimethyl-p-toluidine.
 In para nitroaniline there occurs a -R effect and inductive effect at NO2​ group at para position, so it is the least basic compound.
And lastly aniline is standard; it has very little to negligible inductive effect. So, it is more basic than others.

Hence, the correct order is II>I>IV>III and Option C is correct.

Note: In chemistry, there are three definitions commonly used of the word base, which are known as Arrhenius bases, Bronsted bases and Lewis bases. All definitions agree that bases are substances which react with acids as originally said. Reactions with indicators: bases turn red litmus paper blue, phenolphthalein pink, keep bromothymol blue in its natural color of blue, and turn methyl orange-yellow.
The pH of a basic solution at standard conditions is greater than seven.