The oxygen evolved during photosynthesis comes from water molecules . Which one of the following pairs of elemnets is involved in this reaction ?

Options

A. Manganese and Chlorine
B. Manganese and Potassium
C. Magnesium and Molybdenum
D. Magnesium and Chlorine

Answer

To solve the question regarding which pair of elements is involved in the reaction where oxygen is evolved during photosynthesis from water molecules, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process of Photosynthesis**: Photosynthesis occurs in two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). The question pertains to the light-dependent reactions where water is split to release oxygen.

2. **Identify the Reaction of Water Splitting**: During the light-dependent reactions, water (H2O) undergoes photolysis, which means it is broken down into hydrogen ions (H+), electrons (e-), and oxygen (O2). The reaction can be summarized as:
\[ 2H_2O \rightarrow 4H^+ + 4e^- + O_2 \]

3. **Recognize the Role of Elements**: The splitting of water requires certain elements that act as catalysts or are essential for the process. In this case, manganese (Mn) and chlorine (Cl) are known to play crucial roles in the photolysis of water.

4. **Evaluate the Options**: The given options are:
- A) Manganese and Chlorine
- B) Manganese and Potassium
- C) Magnesium and Molybdenum
- D) Magnesium and Chlorine

Based on our understanding, manganese and chlorine are involved in the light reactions, particularly in the photolysis of water.

5. **Select the Correct Answer**: Therefore, the correct answer to the question is:
**A) Manganese and Chlorine**