To determine which of the given compounds exhibits hydrogen bonding, we need to understand the nature of hydrogen bonding. Hydrogen bonding occurs when hydrogen is directly bonded to highly electronegative atoms like nitrogen (N), oxygen (O), or fluorine (F). Such bonds give rise to a partial positive charge on the hydrogen atom, which can attract lone pairs on other electronegative atoms, leading to hydrogen bonding.
- HCl: In HCl, hydrogen is bonded to chlorine. Although chlorine is electronegative, HCl typically does not participate in hydrogen bonding. Instead, it forms dipole-dipole interactions.
- C\(_2\)H\(_6\) (Ethane): This is a simple hydrocarbon molecule with no electronegative atoms like N, O, or F. Therefore, it cannot participate in hydrogen bonding.
- RCH\(_2\)CHO (Aldehyde): In an aldehyde group, while there is an oxygen atom, the hydrogen atom is not bonded directly to oxygen, nitrogen, or fluorine. Thus, typical hydrogen bonding is not observed.
- RCH\(_2\)NHCH\(_3\) (Amines): Here, the hydrogen atom is bonded to nitrogen, an electronegative atom. This creates conditions favorable for hydrogen bonding as nitrogen has a lone pair that can participate in this bonding.
Therefore, among the options provided, RCH\(_2\)NHCH\(_3\) (Amines) is the correct answer as it can exhibit hydrogen bonding due to the presence of the NH bond, where hydrogen is bonded to nitrogen.