28-29. Rubidium has a naturally occurring radioisotope, 87Rb, that decays via decay into 87Sr with a half-life of 49 billion years (49x109 years). This decay process has been used to date the formation of meteorites and lunar rocks. One meteorite sample containing 87Rb has a measured activity of 0.47 Bq. What mass of 87 Rb is present in the sample, assuming all of the activity comes from 87Rb? mg Careful analysis of a lunar rock sample shows that it contains 1.73 g 87Rb and 67.4 ng of 87 Sr. If all the 87 Sr in the sample came from the decay of 87Rb, how much time has passed since this mineral first crystalized? (This type of analysis provides an estimate for the age of the formation of the moon.) 10^9 F

ing This tye of andysil peovides an etimate for the age of the formation of the mocn]