JAMB - Physics (2012 - No. 39)
A piece of radioactive material contains 1000 atmos. If its half -life is 20seconds, the time taken for 125 atoms to remain is
20 seconds
40 seconds
80 seconds
60 seconds
Објашњење
1000 → 500 → 250 → 125
20 + 20 + 20 = 60s
20 + 20 + 20 = 60s