Assignment 10- Nuclear Physics This assignment is meant for practice and will not be collected or marked. Question 1: The mass MN of neutral 14N is equal to 14.003074 atomic mass units. a) Calculate the mass defect of the nitrogen nucleus 14N. b) Calculate the binding energy of the nitrogen nucleus 14N. c) Calculate the binding energy per nucleon of the nitrogen nucleus 14N. Question 2: A 116 mCi radioactive tracer is made in a nuclear reactor. When it is delivered to a hospital 16 hours later its activity is 96 mCi. The lowest usable level of activity is 11 mCi. 1 Ci is equal to 3.7 x 1010 radioactive decays per second. a) What is the tracer's half-life? b) For how long after delivery is the sample usable? Question 3: A radioactive sample has a half-life of 5.7 days and an initial activity of 1.07 × 105 Bq. a) How many unstable nuclei does the sample initially contains? b) How many days are required for this sample to decay to an activity of 100 Bq? Question 4: How many half-lives must elapse until 98.0% of a radioactive sample of atoms has decayed? Answers: Q1: a) 0.1124 u; b) 104.7 MeV; c) 7.48 MeV/nucleon Q2: a) 59 hours; b) 180 hours Q3: a) 7.6x1010 nuclei; b) 57.4 d Q4: 5.64 half-lives PHY-NYC

Assignment 10- Nuclear Physics This assignment is meant for practice and will not be collected or marked. Question 1: The mass MN of neutral 14N is equal to 14.003074 atomic mass units. a) Calculate the mass defect of the nitrogen nucleus 14N. b) Calculate the binding energy of the nitrogen nucleus 14N. c) Calculate the binding energy per nucleon of the nitrogen nucleus 14N. Question 2: A 116 mCi radioactive tracer is made in a nuclear reactor. When it is delivered to a hospital 16 hours later its activity is 96 mCi. The lowest usable level of activity is 11 mCi. 1 Ci is equal to 3.7 x 1010 radioactive decays per second. a) What is the tracer's half-life? b) For how long after delivery is the sample usable? Question 3: A radioactive sample has a half-life of 5.7 days and an initial activity of 1.07 × 105 Bq. a) How many unstable nuclei does the sample initially contains? b) How many days are required for this sample to decay to an activity of 100 Bq? Question 4: How many half-lives must elapse until 98.0% of a radioactive sample of atoms has decayed? Answers: Q1: a) 0.1124 u; b) 104.7 MeV; c) 7.48 MeV/nucleon Q2: a) 59 hours; b) 180 hours Q3: a) 7.6x1010 nuclei; b) 57.4 d Q4: 5.64 half-lives PHY-NYC