Blood pH is controlled by concentration `H_(2)CO_(3)and HCO_(3)^(-)`of and In presence of `NaHCO_(3)` pH of blood is

Options

A. Increased
B. Decreased
C. No change
D. Statement is wrong

Explanation

To determine the effect of sodium bicarbonate (NaHCO₃) on blood pH, we can analyze the role of carbonic acid (H₂CO₃) and bicarbonate ions (HCO₃⁻) in the blood's buffering system.

### Step-by-Step Solution:

1. **Understanding the Buffer System**:
- Blood pH is maintained through a buffer system primarily involving carbonic acid (H₂CO₃) and bicarbonate ions (HCO₃⁻).
- The equilibrium can be represented as:
\[ \text{H}_2\text{CO}_3 \rightleftharpoons \text{HCO}_3^- + \text{H}^+ \]

2. **Role of CO₂**:
- Carbon dioxide (CO₂) in the blood reacts with water to form carbonic acid:
\[ \text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \]
- This reaction is crucial as it helps regulate the concentration of H₂CO₃ and HCO₃⁻.

3. **Effect of Adding NaHCO₃**:
- When sodium bicarbonate (NaHCO₃) is added to the blood, it dissociates into sodium ions (Na⁺) and bicarbonate ions (HCO₃⁻):
\[ \text{NaHCO}_3 \rightarrow \text{Na}^+ + \text{HCO}_3^- \]
- The increase in HCO₃⁻ concentration shifts the equilibrium of the buffer system:
\[ \text{H}_2\text{CO}_3 \rightleftharpoons \text{HCO}_3^- + \text{H}^+ \]
- According to Le Chatelier's principle, adding more HCO₃⁻ will shift the equilibrium to the left, reducing the concentration of H⁺ ions.

4. **Effect on pH**:
- Since pH is inversely related to the concentration of H⁺ ions, a decrease in H⁺ concentration will result in an increase in pH.
- Therefore, the addition of NaHCO₃ will lead to an increase in blood pH.

5. **Conclusion**:
- In the presence of NaHCO₃, the pH of blood increases due to the common ion effect, which reduces the concentration of H⁺ ions.

### Final Answer:
The pH of blood increases in the presence of NaHCO₃.