The buffer solution present in blood is

Options

A. `CH_3 COOH + CH_3 COONa`
B. `H_2 CO_3 + NaHCO_3`
C. `NaOH + NaCl`
D. `Al(OH)_3 + AlCl_3`

Answer

### Step-by-Step Solution:

1. **Understanding Buffer Solutions**:
A buffer solution is defined as an aqueous solution that can resist changes in pH when small amounts of an acid or a base are added. It typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid.

2. **Identifying the Buffer in Blood**:
The specific buffer solution present in blood is crucial for maintaining the pH of blood within a narrow range, which is essential for proper physiological function.

3. **Components of the Blood Buffer**:
The buffer system in blood primarily consists of carbonic acid (H₂CO₃) and its conjugate base, bicarbonate (HCO₃⁻).

4. **Function of the Buffer**:
When acids (H⁺ ions) are added to the blood, the bicarbonate ions can react with them to form carbonic acid, thus minimizing the change in pH. Conversely, if a base (OH⁻ ions) is added, the carbonic acid can dissociate to release H⁺ ions, again helping to maintain the pH.

5. **Conclusion**:
Therefore, the buffer solution present in blood is carbonic acid and bicarbonate, which can be summarized as:
- **Buffer Solution**: Carbonic Acid (H₂CO₃) + Bicarbonate (HCO₃⁻)