<P> An example of a spontaneous (without addition of an external energy source) decomposition is that of hydrogen peroxide which slowly decomposes into water and oxygen (see video at right): </P> <Dl> <Dd> 2 H O → 2 H O + O </Dd> </Dl> <Dd> 2 H O → 2 H O + O </Dd> <P> It should also be noted that this reaction is one of the exceptions to the endothermic nature of decomposition reactions . Because it occurs spontaneously, it is, by definition, an exothermic reaction . </P>

Which of the following can be decomposed by the action of light