Final answer:
A spontaneous reaction releases free energy and moves to a more stable state. Fire and explosion are examples of chemical reactions that can be associated with the presence of sparks.
Step-by-step explanation:
A spontaneous reaction is one which releases free energy and moves to a more stable state. Instantaneous reactions occur rapidly with sudden release of energy.
When it comes to spark, it can be associated with a fire or an explosion, both of which can be considered as chemical reactions. In the case of a fire or an explosion, the release of energy occurs rapidly and can often be accompanied by the presence of sparks.
For example, fireworks exploding in the air before the actual display is a chemical reaction that involves the rapid release of energy, resulting in the formation of sparks. Similarly, in a fire, the combustion of fuel leads to the release of energy, which can manifest as sparks in the air.