Question

Assertion: The buffer \[\dfrac{{HCOOH}}{{HCOONa}}\] will have pH less than 7.
Reason: Conjugate base of a weak acid is a strong base.
A.Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B.Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C.Assertion is true but Reason is false.
D.Assertion is false but Reason is true
E.Both Assertion and Reason are false.

Answer 1

Hint: \[\dfrac{{HCOOH}}{{HCOONa}}\] contains weak formic acid $HCOOH$ and salt Sodium Format $HCOONa$.

Complete step by step answer:
Buffers are the solutions which maintain a relatively constant pH when an acid or base is added. It buffers other molecules in the solution from the effect of the added acid or base.
Buffers either contain a weak base and its conjugate acid or a weak acid (HA) and its conjugate base $({A^ - })$ .
The buffer \[\dfrac{{HCOOH}}{{HCOONa}}\] is an acidic buffer which contains formic acid HCOOH which is a weak acid and salt Sodium Format HCOONa, the salt of its conjugate base, the format anion, $HCO{O^ - }$ with strong base NaOH.
It will have pH less than 7 as the solution will be acidic.
Here, Assertion and Reason both are true but the Reason is not the correct explanation of the Assertion.

So, the correct answer id option (b).

Note: Buffer contains a weak acid and its conjugate base so that they can absorb excess ${H^ + }$ ions or $O{H^ - }$ ions thereby maintaining a steady pH in the solution.