The products are stable gases, i.e., they're very low on the vertical energy line. The rapid production of gases, coupled with large bursts of thermal energy, give explosives the power to do work on objects - very rapid work. One was covered so as to be light-proof. The other was placed in a beam of light. The covered sample did not change in appearance.
Silver halides are sensitive to light.
Photographic films contain silver halides in their emulsions. They photoreact with light to different degrees depending on light intensity. This leads to negatives of varying shades of gray, and eventually to positive pictures. It can bond to iron in hemeglobin making a very stable iron-carbon bond. Oxygen is a weaker ligand.