Which of the following is a physical change? A. a newspaper burns when placed in a fire.
B. an iron chair rusts when left outside
C. a sample of water boils and releases gas.
D. a plant changes carbon dioxide and water into sugar

It’s C. This is because all of the other options you can’t turn back but if you boil water, the gas can turn back by condensation. If a newspaper burns it’s gone. If the chair rust you can only scrape off the rust. If the plant changes the CO2 you aren’t getting it back. At least not easily