Complete these statements, supplying the proper quantity.
(a) A mole of O atoms contains ___ atoms.
(b) A mole of O₂ molecules contains ___ molecules.
(c) A mole of O₂ molecules contains ___ atoms.
(d) A mole of O atoms has a mass of ___ grams.
(e) A mole of O₂ molecules has a mass of ___ grams.
