Which two elements make up the greatest percentages by mass in Earth’s crust? (1) oxygen and potassium
(2) oxygen and silicon
(3) aluminum and potassium
(4) aluminum and silicon

Electric charge is what ? a. kinetic energy b. radiation c. discovery d. electricity

In which situation can a mixture always be called a solution

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.