Question

Which of the following statement is correct?
(A). The stronger the acid, the weaker will be its conjugate base
(B). The stronger the acid, the stronger will be its conjugate base
(C). The larger the pKa of the conjugate acid, the weaker is its base
(D). The larger the pKa of the conjugate acid, the stronger is its base
Choose the correct answer from the options given below:

• A. D only
• B. B and C only
• C. A and D only
• D. B only

Hint:

A strong acid dissociates completely to form its conjugate base, which is very weak and has low affinity for a proton. A weak acid dissociates only partly and thus, its conjugate base is stronger and has higher affinity for a proton.

Answer 1

The Correct Option is C

The strength of an acid is inversely related to the strength of its conjugate base.
• Strong acids dissociate completely, producing stable conjugate bases with little tendency to accept a proton. Therefore statement (A) is correct, that is, the stronger the acid, the weaker is the conjugate base.
• pKa value: is the indicator of acid strength; the larger the pKa value, the weaker the acid.
Therefore a higher pKa indicates a weaker acid, which leads to a stronger conjugate base and statement (D) is correct, that is, the larger the pKa value of the conjugate acid, the stronger its base. Statements B and C are incorrect.