<p>CHAPTER 25 CHEMISTRY REVIEW QUESTIONS</p><p>21 The initial mass of a radioisotope is 10.0 g. If the radioisotope has a half-life of 2.75 years, how much remains after four half-lives?</p><p>24 Graphing A sample of polonium-214 originally has a mass of 1.0 g. Express the mass of polonium-214 remaining as a percent of the original sample after a period of one, two, and three half-lives. Graph the percent remaining versus the number of half-lives. Approximately how much time has elapsed when 20% of the original sample remains? Each half-life corresponds to a 50% reduction in the amount remaining.</p><p>37 Compare and contrast chemical reactions and nuclear reactions in terms of energy changes and the particles involved.</p><p>38 Match each numbered choice on the right with the correct radiation type on the left. (25.1) a. alpha 1. high speed electron s 2. 2+ charge 3. no charge 4. helium nucleus 5. blocked very easily b. beta 6. electromagnetic radiation c. gamma 39 What is a nucleon? 40 What is the difference between a positron and an electron? 41 Describe the differences between a balanced nuclear equation and a balanced chemical equation. 42 What is the strong nuclear force? On what particles does it act? 49 Why are some radioisotopes found in nature, while others are not? </p><p>Thinking problem 49 Why are some radioisotopes found in nature, while others are not? 87 Write a balanced nuclear equation for the positron emission of nitrogen-13. (Positron is an electron with +1 charge)</p><p>Take home quiz 69 Complete the following equations:</p><p>70 Write a balanced nuclear equation for the alpha decay of americium-241.</p><p>71 Write a balanced nuclear equation for the beta decay of bromine-84.</p><p>72 Write a balanced nuclear equation for the beta decay of selenium-75.</p><p>77 The half-life of tritium (Hydrogen-3) is 12.3 years. If 48.0 mg of tritium is released from a nuclear power plant during the course of a mishap, what mass of the nuclide will remain after 49.2 years? After 98.4 years?</p><p>78 Technetium-104 has a half-life of 18.0 minutes. How much of a 165.0 g sample remains after 90.0 minutes?</p><p>101 Identify each of the following as a chemical property or a physical property. a) The element mercury has a high density. c. Zinc oxidizes when exposed to air. b. Solid carbon dioxide sublimes at room temperature. d. Sucrose is a white crystalline solid. 105 If the volume of a sample of chlorine gas is 4.5 L at 0.65 atm and 321 K, what volume will the gas occupy at STP?</p><p>106 The temperature of 756 g of water in a calorimeter increases from 23.2°C to 37.6°C. How much heat was given off by the reaction in the calorimeter?</p>