¹³¹I is a dangerous fission product because iodine is preferentially absorbed by the thyroid gland in children. It has a half-life of about 8 days and emits a β-particle with average energy 180 keV. (Ignore theγ-radiation that accompanies this decay (see Example 20.2.)) How much mass of ¹³¹I (per gram of thyroid tissue) must a child absorb to suffer an equivalent dose of 10 mSv to the thyroid? What is the activity per gram of this radiation dose (in curies) (see Problem 20.10)?