Which statement correctly describes a physical change?

involves breaking and creating chemical bonds but not changing a phase

may involve a change in phase but does not involve a change in the molecular structure

may involve converting two or more substances into new substances

involves changes at the molecular level

involves energy transfer and change in color

What is the subscript for oxygen in its molecular formula

A5.00 g of a in . g of at aa 5.00 g of b in . g of .?at .

How is electrolysis most commonly used to produce an energy source? a - splitting water molecules produces oxygen, which organisms breathe to fuel their bodies. b - splitting water molecules produces hydrogen gas, which is used to power machines through hydrogen fuel cells. c - splitting carbon dioxide molecules produces coal, a form of carbon that can be burned to produce heat. d - splitting carbon dioxide molecules produces natural gas, which can be burned to generate electricity in power plants.