¿las reacciones químicas se clasifican en cambio físicos o químicos?¿por que?

What is the oxidation state of each individual carbon atom in c2o42−?

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

Pls i will do pls imma diewhat forms white light? (4 points)a. combination of all wavelengths of ultraviolet light b. combination of all wavelengths of visible lightc. absorption of electromagnetic waves d. absorption of infrared rays