Asked in NUMS 2019 (cancelled sitting) 2019Moderate

All of the following substances can act as Lewis acids except:

Correct answer: D. H2O

  • A. BF3
  • B. H+
  • C. AlCl3
  • D. H2O

Explanation

All the given options, BF3, H+, AlCl3, and H₂O, can act as Lewis acids since they can accept electron pairs. However, in H₂O, the oxygen atom is already sharing its two lone pairs of electrons with two hydrogen atoms, so it cannot accept more electrons easily and hence cannot act as a Lewis acid easily. So the best possible answer is D) water.

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