How is the phase of a substance a physical property?

Which diagram shows the correct way to represent an ionic compound of magnesium oxide?

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.

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false