Which set of solutes will form a buffer when dissolved in water to make 1 liter of solution?

Correct answer: A. 4 moles of NH₃ with 2 moles of HCl

  • A. 4 moles of NH₃ with 2 moles of HCl
  • B. 0.0002 mole of HCl
  • C. 2 moles of NaCl with 2 moles of HCl
  • D. 4 moles of CH₃COOH with 4 moles of NaCl

Explanation

NH₃ is a weak base, and partial neutralization with HCl produces NH₄⁺ (its conjugate acid). After reaction, both NH₃ and NH₄⁺ are present → a classic buffer pair. So only Option A forms a buffer.

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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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