Why is OH⁻ ion a strong base in water solution?

Correct answer: B. OH⁻ is the conjugate base of H₂O

  • A. OH⁻ is only the base in the solution
  • B. OH⁻ is the conjugate base of H₂O
  • C. Strong bases dissolve completely in water and produce OH⁻ ions
  • D. All bases react with water to produce OH⁻ ions

Explanation

OH⁻ is considered a strong base in water because it is the conjugate base of water, H₂O. When water loses a proton, it forms OH⁻. As a strong base, OH⁻ can readily accept protons. Option B is correct because it correctly identifies OH⁻ as the conjugate base of H₂O. Option A is incorrect as it oversimplifies the role of OH⁻. Option C is misleading because it does not address why OH⁻ is inherently a strong base, and Option D is incorrect because not all bases follow this behavior.

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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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