Radioactive iodine (radioiodine) is given to patients with some forms of thyroid cancer in order to destroy the cancer cells. 131I has a half-life of 8 days. Women who have been treated with 131I are advised to not become pregnant for 180 days (approximately 6 months) to avoid the radioactive contamination of a developing fetus. If a woman has been given a dose of 10 mCi (millicurie, a measurement of radiation), how much 131I will still be in her system when she can safely become pregnant? a.3.125% of the original isotope

b. There will be no iodine-131 left in her system after 180 days.

c.1.7 x 10-6 mCi

d.22.5 x 10-6 mCi

How many electrons does silver have to give up in order to achieve a sido noble gas electron configuration?

The scheme below is from a series of reactions that are part of a synthesis of vitamin a. answer the following questions with reference to this scheme. (i) what is "reagent a"? (ii) draw a step-by-step mechanism which explains the formation of compound c from compound b (iii) which reagents would you use to form compound e from compounds c and d (reagents b and c)? for each reagent suggested above in (ii) explain the role of the reagent in the reaction to (iv) form compound e. you may wish to do this by drawing a mechanism. 1. addition of reagent a но reagent a 2. н, о" thо oh нон-с compound a. compound b. compound c .ch-оh 1. reagent b "сно 2. reagent c сh oh compound e. compound d.

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?