Which of the following factors are favorable for the formation of oxyhaemoglobin ?
I. high `pO_2`
II. low `pCO_2`
III. lesser `H^+` concentration
IV. lower temperature

Options

A. I,II and III
B. I,III and IV
C. I and IV
D. I, II , III and IV

Answer

To determine which factors are favorable for the formation of oxyhemoglobin, we need to analyze each of the given options in the context of how hemoglobin binds with oxygen.

### Step-by-Step Solution:

1. **Understanding Oxyhemoglobin Formation**:
- Oxyhemoglobin is formed when hemoglobin binds with oxygen. This process is influenced by various physiological factors.

2. **Evaluating Each Factor**:
- **Factor I: High pO2**:
- A high partial pressure of oxygen (pO2) facilitates the binding of oxygen to hemoglobin. The greater the pO2, the more oxygen molecules are available to bind with hemoglobin, thus favoring the formation of oxyhemoglobin.
- **Conclusion**: Favorable for oxyhemoglobin formation.

- **Factor II: Low pCO2**:
- A low partial pressure of carbon dioxide (pCO2) is favorable for the formation of oxyhemoglobin. High levels of CO2 can lead to a decrease in pH (more acidic), which promotes the release of oxygen from hemoglobin (Bohr effect).
- **Conclusion**: Favorable for oxyhemoglobin formation.

- **Factor III: Lesser H+ Concentration**:
- A lower concentration of hydrogen ions (H+) indicates a higher pH (less acidic). High H+ concentration (low pH) promotes the release of oxygen from hemoglobin. Therefore, lesser H+ concentration is favorable for the binding of oxygen to hemoglobin.
- **Conclusion**: Favorable for oxyhemoglobin formation.

- **Factor IV: Lower Temperature**:
- Lower temperatures favor the binding of oxygen to hemoglobin. Higher temperatures can cause hemoglobin to release oxygen more readily, thus lower temperatures are favorable for the formation of oxyhemoglobin.
- **Conclusion**: Favorable for oxyhemoglobin formation.

3. **Final Conclusion**:
- All four factors (I, II, III, IV) are favorable for the formation of oxyhemoglobin. Therefore, the correct answer is that all the statements are correct.

### Answer:
All factors (I, II, III, IV) are favorable for the formation of oxyhemoglobin.