🤓 Based on our data, we think this question is relevant for Professor Poehlmann & Waymouth's class at STANFORD.
Solution: Naturally occuring iodine has an atomic mass of 126.9045. A 12.3849-g sample of iodine is accidentally contaminated with an additional 1.00070 g of 129l, a synthetic radioisotope of iodine used in the treatment of certain diseases of the thyroid gland. The mass of 129l, is 128.9050 amu. Find the apparent "atomic mass" of the contaminated iodine.