Wich substances is most likely to form in a precipitation reaction?

What is the formula that this ionic compounds could form sr2+p3-o2-

Heat energy, carbon dioxide, and water are released through which process? a. photosynthesis b. depolymerization c. digestion d. cellular respiration

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium