An acidic buffer is obtained on mixing:

Question

Canvas Classes · Accepted Answer

Acidic buffer = weak acid + its conjugate base (salt), with pH < 7.

Step 1 — Analyse each option:

(1) 100 mL 0.1M  + 100 mL 0.1M NaOH:
Moles: acid = 0.01, base = 0.01  complete neutralisation  only  (basic salt solution, not a buffer) ✗

(2) 100 mL 0.1M HCl + 200 mL 0.1M NaCl:
HCl is strong acid, NaCl is neutral salt  not a buffer ✗

(3) 100 mL 0.1M  + 200 mL 0.1M NaOH:
Moles: acid = 0.01, base = 0.02  NaOH in excess  basic solution ✗

(4) 100 mL 0.1M HCl + 200 mL 0.1M :
Moles: HCl = 0.01,  =

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