9) How many molecules of nitrogen monoxide are in a 22.5 gram sample? A) 5.86 x 103 B) 7.33 x 1023 C) 4.51 x 1023 D) 4.06 x 1023 N Os 2259 ( 10) When water is heated, bubbles form in the water. Is this evidence of a chemical reaction? Why? A) No, boiling water is a physical change. BYes, the formation of a gas is evidence of a chemical reaction. C) No, the formation of gas bubbles is a secondary chemical reaction which is ignored. D) Yes, the formation of a gas is proof a new compound has been made.