How many electrons, protons and photons are involved in the lysis of water to evolve one molecule of oxygen ?

Options

A. ` 4e^(-), 4H^(+)` and 4 photons
B. ` 4e^(-), 4H^(+)` and 8 photons
C. ` 2e^(-) , 2H^(+)` and 8 photons
D. `2e^(-) and 2H^(+)` and 4 photons

Answer

To solve the question of how many electrons, protons, and photons are involved in the lysis of water to evolve one molecule of oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photolysis of Water**:
- Photolysis of water is the process where water molecules are split into oxygen, protons (hydrogen ions), and electrons in the presence of light. This process occurs during the light-dependent reactions of photosynthesis.

2. **Chemical Reaction**:
- The balanced chemical equation for the photolysis of water is:
\[ 2 H_2O \rightarrow 4 H^+ + 4 e^- + O_2 \]
- From this equation, we can see that two molecules of water (H2O) are split to produce one molecule of oxygen (O2).

3. **Counting Electrons**:
- From the equation, for every two water molecules that are split, four electrons (4 e^-) are released. Therefore, to evolve one molecule of oxygen, four electrons are involved.

4. **Counting Protons**:
- The reaction also produces four protons (4 H^+) for every two water molecules. Thus, to evolve one molecule of oxygen, four protons are involved.

5. **Counting Photons**:
- The process of photolysis requires light energy, which is captured in the form of photons. It is known that eight photons are required for the complete process: four photons are needed for the actual breakdown of water and four additional photons are required for the transport of the oxygen to photosystem II.

6. **Final Count**:
- Therefore, for the evolution of one molecule of oxygen, the counts are:
- **Electrons**: 4
- **Protons**: 4
- **Photons**: 8

7. **Conclusion**:
- The correct answer is that 4 electrons, 4 protons, and 8 photons are involved in the lysis of water to evolve one molecule of oxygen.

### Summary:
- **Electrons**: 4
- **Protons**: 4
- **Photons**: 8