Final answer:
The compound that is photosensitive and releases brown fumes and a green compound upon reaction with sunlight is copper chloride.
Step-by-step explanation:
The compound that is photosensitive and releases brown fumes and a green compound upon reaction with sunlight is copper chloride. When exposed to sunlight, copper chloride decomposes into copper(I) chloride which is green, and chlorine gas which appears as brown fumes. Color and light absorption are important concepts in this process.
A compound's color is due to light that is transmitted or reflected, with reflected or transmitted light being complementary to the light that is absorbed. The energy of a photon of light is inversely proportional to its wavelength, so the color of a complex depends on the energy of the light it absorbs.
For example, in coordination compounds of chromium, differences in ligand field strength lead to different colors observed due to the varying energies of absorbed light.