Indicate the type of observation that is best represented by the figures below.

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.

What type of reaction fuels the processes seen here?

What is a number added in front of a formula in order to balance the equation