Question

Arrange the following in the increasing order of solubility in water:

i) $C_6{H}_5{NH}_2$

ii) $(C_2{H}_5{)}_{2}NH$

iii) $C_2{H}_5{NH}_2$

• A. i < ii < iii
• B. ii < i < iii
• C. iii < i < ii
• D. iii < ii < i

Answer 1

The correct option is D iii < ii < i

The increasing order of solubility in water; is iii) $C_2{H}_5{NH}_2$ < ii) $(C_2{H}_5{)}_{2}NH$ < i) $C_6{H}_5{NH}_2$

The extent of $H$ bond formation in iii) $C_2{H}_5{NH}_2$ is minimum as it has only one $H$ attached to $N.$ Hence, it has at least solubility.

i) $C_6{H}_5{NH}_2$ has maximum solubility as it can form hydrogen bonds and is polar due to resonance of lone pair of electrons on $N$ with benzene rings. Higher is the polarity of the molecule, higher will be its solubility.

So, the correct option is $D$