What color range is primarily absorbed by pure water?

The correct answer highlights that pure water primarily absorbs light in the red-orange range. Water molecules have specific vibrational and rotational transitions that lead to the absorption of infrared and near-infrared light, which often overlaps with the red and orange parts of the spectrum. As a result, light in these wavelengths does not penetrate very deeply into water, but rather gets absorbed quickly.

Understanding the light absorption characteristics of water is crucial in various fields including aquatic ecology, oceanography, and environmental science, as it plays a role in the heating of water bodies and impacts photosynthesis in aquatic plants.

The other options do not represent the primary absorption of pure water. Blue light is actually scattered in water, which is why large bodies of water often appear blue. Green light has moderate absorption but is much less absorbed than red-orange light. Ultraviolet light can also be absorbed by water, but its absorption properties are more relevant to topics like UV sterilization and are not the primary range associated with pure water in terms of visible light absorption.