A sample carbon-12 has a mass of 6 grams how many atoms are in carbon-12

Ibeg i need 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

How does kepler second law of planetary motion overthrow one of the basic beliefs of classical astronomy