Gregory is a geologist who went on an excursion to Australia. While hiking in a cave, Gregory found two radioactive rocks containing Uranium. Gregory then brought the rocks back to his lab in Germany to conduct tests. Gregory discovered that rock A had high amounts of the original uranium isotope present, and low amounts of the daughter uranium isotope present. In rock B, however, there were low amounts of the original uranium isotope present and high amounts of the daughter uranium isotope present. Which rock, rock A or rock B, had been decaying over a shorter period of time?
Answer:
rock A