An acid is not strong if its conjugate base:

Correct answer: C. Have lower Ka value

  • A. Have higher pKb value
  • B. Highly stable
  • C. Have lower Ka value
  • D. None of the above

Explanation

The strength of an acid is inversely related to the strength of its conjugate base. If an acid has a lower Ka value, it is weaker, meaning it dissociates less in solution. Consequently, its conjugate base is relatively stronger in accepting protons. Therefore, Option C is correct. Option A is incorrect because a higher pKb suggests a weaker base, which would mean the original acid is stronger, not weaker. Option B is incorrect because a highly stable conjugate base usually indicates that the acid is strong. Option D is incorrect because Option C is the correct choice.

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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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