Question

Hydrogen bonding does not play any role in boiling of
A. $N{{H}_{3}}$ ​
B. ${{H}_{2}}O$
C. $HI$
D. ${{C}_{2}}{{H}_{5}}OH$

Answer 1

Hint: Hydrogen bonds can be defined as the attractive force which binds the hydrogen atom of one molecule with the electronegative atom $F,N,O$ of another molecule. In the presence of hydrogen bonding, the boiling point increases.

Complete Step by Step Answer:
The Conditions for making hydrogen bonds are as follows:
- The molecule must contain a highly electronegative atom that is attached to the hydrogen atom to form a covalent bond.
- Higher the electronegativity more is the polarisation of the molecule so that electrons of the covalent bonds are shifted towards the more electronegative atom and make partially positively charged hydrogen atoms.
- Smaller the size of the electronegative atom, the greater is the electrostatic attraction.
- Ammonia, water and ethanol have hydrogen bonding between the electronegative oxygen, nitrogen with hydrogen atoms. Thus hydrogen bonding plays a role in boiling of ammonia, ethanol and water.
- Again hydrogen iodide has no hydrogen bonding between hydrogen and iodide atoms as the iodine atom does not participate in hydrogen bonding. So, Hydrogen bonding does not play any role in boiling of hydrogen iodide.
Thus the correct option is C.

Note: Among the halogen hydrides only hydrogen fluoride contains hydrogen bonding between electronegative fluorine and electropositive hydrogen atom. It has different properties from other halogen hydrides.