The following reaction takes place in the body
`CO_(2)+H_(2)OhArrH_(2)CO_(3)hArrH^(+)+HCO_(3)^(-)`. If `CO_(2)` escapes from the system

Options

A. pH will decrease
B. `[H^(+)]` will diminish
C. `[H_(2)CO_(3)]` will remain unchanged
D. The forward reaction will be favoured

Answer

To solve the problem, we need to analyze the chemical equilibrium involved in the reaction and the effect of CO₂ escaping from the system. Here’s a step-by-step breakdown of the solution:

### Step 1: Write the Reaction and Identify the Equilibrium
The reaction given is:
\[ \text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^- \]

This reaction shows that carbon dioxide (CO₂) reacts with water (H₂O) to form carbonic acid (H₂CO₃), which can further dissociate into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻).

### Step 2: Understand the Effect of CO₂ Escaping
When CO₂ escapes from the system, the concentration of CO₂ decreases. According to Le Chatelier's principle, if a change is made to a system at equilibrium, the system will adjust to counteract that change.

### Step 3: Apply Le Chatelier's Principle
Since CO₂ is a reactant, its removal will shift the equilibrium to the left (toward the reactants) to try to produce more CO₂. This means:
- The formation of H₂CO₃ will decrease.
- The dissociation of H₂CO₃ into H⁺ and HCO₃⁻ will also decrease.

### Step 4: Analyze the Changes in Concentration
1. **Decrease in H₂CO₃**: As CO₂ escapes, the concentration of carbonic acid (H₂CO₃) will decrease.
2. **Decrease in H⁺ and HCO₃⁻**: Since H₂CO₃ dissociates into H⁺ and HCO₃⁻, a decrease in H₂CO₃ will lead to a decrease in both H⁺ and HCO₃⁻ concentrations.

### Step 5: Determine the Effect on pH
The concentration of H⁺ ions is directly related to the pH of the solution. As the concentration of H⁺ decreases, the pH of the solution will increase (become less acidic).

### Step 6: Evaluate the Statements
Now, we can evaluate the statements provided in the question:
1. **Statement 1**: The pH will increase. (Correct)
2. **Statement 2**: H⁺ will diminish. (Correct)
3. **Statement 3**: H₂CO₃ will remain unchanged. (Incorrect, as H₂CO₃ decreases)
4. **Statement 4**: The forward reaction will be favored. (Incorrect, as the backward reaction is favored)

### Final Conclusion
Based on the above analysis, we conclude that:
- The pH increases due to the decrease in H⁺ concentration.
- H⁺ concentration diminishes.
- H₂CO₃ decreases.
- The forward reaction is not favored; rather, the backward reaction is favored.