Ruthenium-106 is used to treat melanoma in the eye. This isotope decays by β− emission with a half-life of 373.59 days. One source of the isotope is reprocessed nuclear reactor fuel. (a) How many protons and neutrons does the 106Ru nucleus contain? There are 44 protons and 62 neutrons in ruthenium-106 nucleus. There are 44 protons and 63 neutrons in ruthenium-106 nucleus. There are 45 protons and 62 neutrons in ruthenium-106 nucleus. There are 45 protons and 61 neutrons in ruthenium-106 nucleus. (b) Could we expect to find significant amounts of 106Ru in ore mined from the ground? Why or why not? No, because such ores are many millions of years old at the least, so if any ruthenium-106 were present initially, it would have decayed to essentially zero. Yes, because since such ores are millions of years old at the least, and the decay rate of ruthenium-106 is very small, there is the probability that at least 5% of the initial amount remains. Yes, because since such ores are millions of years old at the least, and the half-life of ruthenium-106 is closed to 1.2 billion of years, there is the probability that at least 25% of the initial amount remains. (c) Write the decay equation for 106Ru and identify the daughter nucleus. 106Ru → e+ + 106Rh 106Ru → e− + ν +106Rh 106Ru → 2e− + 106Rh 106Ru → e− + 106Rh (d) How many years after 106Ru is implanted in the eye does it take for its decay rate to be reduced by 70%? yr