19.)Heavy water is A.Deuterium Oxide B.Ph7 C.Rain Water D.Tritium Oxide View Answer Correct Answer: A. 20.)Which of the following is not a chemical reaction? (A)Burning of paper (B)Digestion of food (C)Conversion of water into steam (D)Burning of coal View Answer Correct Answer: C. 21.)Which of the following is a physical change? (A)Oxidation (B)Reduction (C)Sublimation (D)Decomposition View Answer Correct Answer: C 22.)Marsh gas is A.NitrogenB.Ethane C.MethaneD.Hydrogen View Answer Correct Answer: C 23.) Which of the following is not a chemical reaction? (A)Burning of paper (B)Digestion of food (C)Conversion of water into steam (D)Burning of coal View Answer Correct Answer: C 24.) Which of the following is a chemical change? (A)Rusting of iron (B)Tempering of iron (C)Melting of iron (D)Bending of iron View Answer Correct Answer: A