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Buffer solutions resist changes in pH because they contain
Aa weak acid and its conjugate base
Ba strong acid and strong base
Conly water
Donly a strong electrolyte
Answer & Solution
Correct answer: A. a weak acid and its conjugate base
1. A buffer is typically a weak acid plus its salt (or weak base plus its salt).
2. Added H⁺ is neutralised by the conjugate base; added OH⁻ is neutralised by the weak acid.
3. Hence the equilibrium shifts only slightly and pH is maintained.
_Source: Maharashtra Balbharati Std XII Chemistry, Ch 3 "Ionic Equilibria" §3.8_
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