Given below are two statements :
Statement (I) : A Buffer solution is the mixture of a salt and an acid or a base mixed in any particular quantities
Statement (II) : Blood is naturally occurring buffer solution whose pH is maintained by H₂ CO₃ / HCO₃ ⊖ concentrations.
In the light of the above statements, choose the correct answer from the options given below :

Solution

Chemistry ma’am · 5 steps

A buffer is not any acid with any salt: it needs a weak acid or base, its own conjugate, and sensible amounts.

1. What a buffer needs. An acidic buffer is a weak acid with a salt of its conjugate base, like CH₃COOH and CH₃COONa. A basic buffer is a weak base with a salt of its conjugate acid, like NH₄OH and NH₄Cl.
2. Why amounts matter. The buffer works only while both partners are present in comparable amounts. In practice this means [salt]/[acid] between about 0.1 and 10, so pH = pKₐ ± 1.

   pH = pKₐ + log[salt]/[acid]

3. Statement I. It is false. A strong acid such as HCl with NaCl is not a buffer at all. Even a correct pair stops buffering if one partner is in large excess.
4. Statement II. It is true. Blood stays near pH 7.4 mainly because of the H₂CO₃/HCO₃⁻ pair: HCO₃⁻ takes up extra H⁺ and H₂CO₃ neutralises extra OH⁻.
5. So. Statement I is false and Statement II is true, which is option (c).

The idea to keep. A buffer is a weak acid or weak base plus its conjugate partner, and both must be present in comparable amounts. Blood's main buffer is H₂CO₃/HCO₃⁻.

Answer from the NTA final answer key. Solution by PrepWiser.