What should be the ratio of concentration of formate ion and formic acid in a buffer solution so that its pH should be 4 ? Around what pH will this buffer have maximum buffere capacity ? `(K_(a)=1.8xx10^(-4))`

Explanation

To solve the problem, we need to find the ratio of the concentration of formate ion (HCOO⁻) to formic acid (HCOOH) in a buffer solution that maintains a pH of 4. We also need to determine the pH at which this buffer has maximum buffer capacity.

### Step-by-Step Solution:

1. **Identify the Given Information:**
- pH = 4
- \( K_a \) (acid dissociation constant for formic acid) = \( 1.8 \times 10^{-4} \)

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