20-21 are together

Use the following information to answer the next two questions Cobalt-60 is a common radiation source used in cancer treatment. The half-life of cobalt-60 is 5.2 years. A cobalt-60 nucleus decays by emitting a beta negative particle and a gamma photon. 20. Which of the following equations correctly describes the decay of cobalt-60? 27 " Co - 60Fe + B+ +v Co -60NI + 0B+7 +v 27 27 " Co -90Fe + 0B + 7 +v Co -60Ni + 0B + 7 +v 21. The percentage of cobalt-60 remaining after 10 years is %. (answer to 3 sig digs) (Record your three-digit answer in the numerical-response section below.) Your answer: 0