How many grams of al2o3 are produced from 4.2 grams of of al reacting with o2?

In any energy conversion, some of the energy is lost to the environment as question 5 options: electrical energy potential energy sound energy thermal energy

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.

Can someone me with questions 12 and 13 plz.