Each element is made up of only one kind

Which substances have the lowest melting points: ionic covalent, or metallic

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

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.