What is released when a election returns to a lower state of energy

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

Ageologist determines that a sample of a mineral can't be scratched by a steel nail but can be scratched by a masonry drill bit. based on this information, the sample mineral has to be softer than a. orthoclase. b. fluorite. c. apatite. d. corundum.

What is the common name for the compound shown here? enter the common name of the compound shown?