The characteristic bright–line spectrum of potassium is produced when electrons A) jump to higher energy levels
B) return to lower energy levels
C) are lost by neutral potassium atoms
D) are gained by neutral potassium atoms
E) are released from the nucleus

The equation below shows a chemical reaction. a + b + heat —> c + d according to the law of conservation of energy, which statement is true? a. the reactants absorb heat because they have less energy than the products. b. the products release heat because they have more energy than the reactants. c. the reactants generate heat because they have more energy than the products. d. the products require heat to form because they have less energy than the reactants.