Question

The hydrogen bonds are encountered in $ HF, H_2O, NH_3 $ and $ HF_2^{- } $ . The relative order of energies of hydrogen bonds is

• A. $ HF > H_{2}O > NH_{3} >HF_{2}^{-} $
• B. $ H_{2}O > HF_{2}^{-} > HF >NH_{3} $
• C. $ HF > HF_{2}^{-} >H_{2}O > NH_{3} $
• D. $ HF_{2}^{-} > HF >H_{2}O > NH_{3} $

Answer 1

Answer: (D)

When a hydrogen bond is sandwitched between two highly electronegative elements $(F, O, N)$, it shows a unique property to form a bridge between them which is termed as hydrogen bond. Its strength depands upon the electronegativity of associated atom. Thus, the order of hydrogen bond must be
$ HF_2^- > HF > H_2O > NH_3$