নিচের কোনটি বাফার দ্রবণ?

The correct answer is: CH₃COOH & CH₃COONa (acetic acid & sodium acetate)

Explanation:

A buffer solution is a solution that can resist changes in pH when small amounts of acid or base are added. It contains a weak acid and its conjugate base (or a weak base and its conjugate acid).

• CH₃COOH (acetic acid): This is a weak acid.
• CH₃COONa (sodium acetate): This is the conjugate base of acetic acid.

The combination of acetic acid and sodium acetate can work together to neutralize small changes in pH.

Let's analyze the other options:

• NaCl & NaOH: This is a strong base (NaOH) and its conjugate acid (NaCl). Strong bases readily dissociate in water, so this solution wouldn't function effectively as a buffer.
• HCl & NH₄Cl: This is a strong acid (HCl) and its conjugate base (NH₄Cl). Similar to the previous option, a strong acid wouldn't be suitable for a buffer solution.
• CH₃COOH & HCl: This is a mixture of a weak acid (acetic acid) and a strong acid (HCl). The strong acid would overpower the buffering capacity of the weak acid.
• NaOH & Na₂CO₃: This is a strong base (NaOH) and its conjugate acid (Na₂CO₃). As mentioned earlier, strong bases aren't ideal for buffers.
• HCl & NaCl: This is again a strong acid (HCl) and its conjugate base (NaCl). Not suitable for a buffer.