Giancoli Ch. 30 – p. 860, Problems #37, 39, 40, 42, 55, 59, 61, 66, 67a, 69 key

37a) 1.5 x 10-10 y
37b) 2.3 h
39) 0.0625
40) 0.015625
42) 7 α particles; 4 β particles
55) thorium-232 -> radium-228 -> actinium-228 -> thorium-228 -> radium-224 -> radon-220; uranium-235 -> thorium-231 -> protactinium-231 -> actinium-227 -> thorium-227 -> radium-223
59) 2.3 x 104 y
61) 41 y
66) 193 y
67a) iridium-191
69) 550 MeV; 2.5 x 1012 J