question_answer 1)

  Hydrogen bonds are formed in many compounds e.g.,\[{{H}_{2}}O,HF,N{{H}_{3}}\]. The boiling point of such compoundsdepends to a large extent on the strength of hydrogen bondand the number of hydrogen bonds. The correct decreasingorder of boiling points of above compounds is: (a) \[HF>{{H}_{2}}O>N{{H}_{3}}\]                                                             (b) \[{{H}_{2}}O>HF>N{{H}_{3}}\] (c) \[N{{H}_{3}}>HF>{{H}_{2}}O\]                                                             (d) \[N{{H}_{3}}>{{H}_{2}}O>HF\]

Answer:

  (b)      

Compound	Boiling point
\[{{H}_{2}}O\]	\[373.0K\]
\[HF\]	\[292.4K\]
\[N{{H}_{3}}\]	\[239.6K\]