• Radioactive tracers. Radioactive isotopes are often intro- duced into the body through the bloodstream. Their spread through the body can then be monitored by detecting the appearance of radiation in different organs. I, a B emitter with a half-life of 8.0 d, is one such tracer. Suppose a scientist introduces a sample with an activity of 375 Bq and watches it spread to the organs. (a) Assuming that the sample all went to the thyroid gland, what will be the decay rate in that gland 24 d (about 2 weeks) later? (b) If the decay rate in the thyroid 24 d later is actually measured to be 17.0 Bq, what percent of the tracer went to that gland? (c) What isotope remains after the I- 131 decays?

• Radioactive tracers. Radioactive isotopes are often intro- duced into the body through the bloodstream. Their spread through the body can then be monitored by detecting the appearance of radiation in different organs. I, a B emitter with a half-life of 8.0 d, is one such tracer. Suppose a scientist introduces a sample with an activity of 375 Bq and watches it spread to the organs. (a) Assuming that the sample all went to the thyroid gland, what will be the decay rate in that gland 24 d (about 2 weeks) later? (b) If the decay rate in the thyroid 24 d later is actually measured to be 17.0 Bq, what percent of the tracer went to that gland? (c) What isotope remains after the I- 131 decays?