statement, "In a chemical reaction, matter is neither created nor destroyed" is called A) the Law of Conservation of Mass B) the Law of Definite Proportions. C) the Scientific Method D) the Law of Multiple Proportions. E) Dalton's Atomic Theory 9) The 10) Without using a calculator, solve the following problem: 10) 1105)(1 102)]2 (1 10-10) A) 1 10-6 B) 1 1034 D) 1 Ã 1024 11) Round off 00507506 to four significant figures A) 5100 B) 5076 C) 0051 D) 5.075105 12) A substance that can't be chemically broken down into simpler substances is A) a compound B) an element. C) an electron D) a heterogeneous mixture. E) a homogeneous mixture. 12) 13) How many cm are in 20 2 ft? A) 616 cm B) 7.95 cm C) 51.2 cm 13) D) 0.663 cm E) 242 cm 14) What does "X" represent in the following symbol? 28 14 14) A) ruthenium B) zinc C) sulfur D) silicon E) nicke 15) Identify a cation. 15) A) an atom that has gained an electron C) an atom that has lost a proton B) an atom that has gained a neutrorn D) an atom that has lost an electron 16) Which of the following elements is a alkali metal? 16) A) Ca B) U 17) Isotopes differ in the number of 17) A) neutrons. B) electrons C) neutrons and protons D) gamma particles. E) compounds