Excitation of chlorophyll by light is

Options

A. Exergonic reaction
B. Anabolic reaction
C. Photochemical reaction
D. Photooxidation reaction.

Answer

### Step-by-Step Solution:

1. **Understanding Chlorophyll**: Chlorophyll is a pigment found in plants, primarily chlorophyll A, which plays a crucial role in photosynthesis by absorbing light energy.

2. **Absorption of Light**: When light strikes the chlorophyll molecules, they absorb specific wavelengths of light, primarily in the blue and red regions of the spectrum.

3. **Excitation of Electrons**: The absorbed light energy excites electrons in the chlorophyll, raising them to a higher energy state. This process is essential for initiating the photosynthetic reactions.

4. **Release of Free Energy**: As the electrons are excited and released from the chlorophyll, they generate free energy. This energy is vital for the subsequent reactions in photosynthesis.

5. **Transfer of Electrons**: The excited electrons are then transferred to a higher energy center within the chlorophyll complex. This transfer is crucial for the continuation of the photosynthetic process.

6. **Water Splitting**: At this higher energy center, the electrons participate in the splitting of water molecules (photolysis). This reaction releases oxygen (O2) as a byproduct and produces hydrogen ions (H+).

7. **Conclusion**: The entire process of chlorophyll absorbing light and subsequently exciting electrons is classified as a photochemical reaction, which is a key component of photosynthesis.

### Final Answer:
The excitation of chlorophyll by light is a photochemical reaction.

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