ACS Chemistry Practice Exam 2025 – The All-in-One Guide to Exam Success!

The correct statement about the relationship between wavelength and the energy of a photon is that as the wavelength decreases, energy increases. This relationship is described by the equation:

\[ E = \frac{hc}{\lambda} \]

where \( E \) is the energy of the photon, \( h \) is Planck's constant, \( c \) is the speed of light, and \( \lambda \) is the wavelength. According to this equation, energy is inversely proportional to wavelength. Therefore, when the wavelength (\( \lambda \)) becomes smaller (or decreases), the energy (\( E \)) of the photon correspondingly becomes larger. This inverse relationship means that photons with shorter wavelengths (such as ultraviolet light) carry more energy compared to those with longer wavelengths (such as infrared light).

Higher energy photons, therefore, correspond to lower wavelengths. This fundamental concept in quantum mechanics clarifies why the relationship described in the chosen statement holds true.