Two sealed gamma sources have the same activity when placed in storage. Source P has a half-life of 2 days. Source Q has a half-life of 20 years. Which comparison is correct after 8 days?
Neither has lost much of its activity; both need precautions for similar times.
P has lost most of its activity; Q needs precautions for much longer.
Q has lost most of its activity; P needs precautions for much longer.
Both have lost most of their activity; both need precautions for similar times.