PhysicsEasy183×since 2002Q6077Starting with a sample of pure 66Cu,78{}^{66}Cu,{7 \over 8}66Cu,87 of it decays into ZnZnZn in 151515 minutes. The corresponding half life isA151515 minutesB101010 minutesC7127{1 \over 2}721 minutesD555 minutesCheck answerSkip