Which of the following is not a base?
Correct answer: B. BF₃ (Boron Trifluoride)
- A. NH₃ (Ammonia)
- B. BF₃ (Boron Trifluoride)
- C. KOH (Potassium Hydroxide)
- D. PH₃ (Phosphine)
Explanation
The correct answer is Option B: BF₃. Boron Trifluoride (BF₃) is not a base; it acts as a Lewis acid because it can accept a pair of electrons due to the electron deficiency of boron. Option A: NH₃ is a base because it can accept a proton to form NH₄⁺. Option C: KOH is a strong base as it dissociates in water to release OH⁻ ions. Option D: PH₃ can act as a base by donating a pair of electrons, although it is not as commonly recognized as a base as NH₃ or KOH.
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About Acids, Bases and Salts
Acid and base behaviour is explained through the Bronsted-Lowry transfer of protons and the Lewis donation or acceptance of electron pairs. The topic includes pH, pOH, ionisation and water equilibrium, plus salt formation and hydrolysis, where a salt solution may become acidic, basic or neutral.
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