<prompt> Iridium 192 half life2.7 days8 days74 days16 hours  <response>: Ans. c 74 daysRef: Basic radiological physics 2nd ed. 180 Iridium-192, emits gamma rays. It has energy of 0.4MeV. Tl2 of iridium 192: 74 daysImportant Half Life of Radionuclides Gold-198: 2.7 days Iodine- 123: 13.3 hours Iodine-131: 8 days Phosphorus-32: 14.3 days Yttrium 90: 64 hours Cobalt-60: 5.26 years Caesium-137: 30 years Radium-226: 1620 years 