At which wavelength is light most absorbed by chlorophyll a?

Chlorophyll a predominantly absorbs light in the blue-violet region and the red region of the electromagnetic spectrum. The light wavelengths around 400 nm fall into the blue-violet range, where chlorophyll a exhibits significant absorption. This absorption is crucial for photosynthesis, as it allows the chlorophyll molecules to capture light energy, which is then converted into chemical energy for plant growth and energy production.

While chlorophyll a does absorb light at other wavelengths, such as in the red region around 660-680 nm, the most effective absorption occurs at about 430-450 nm, aligning closely with the 400 nm wavelength indicated in the question. Thus, the absorption peak around 400 nm is essential for maximizing the efficiency of photosynthesis in plants.