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nitrogen-16 has an original sample soze of 50.0grams. How much of the sample will remain after a total time of 28.52 seconds has passes?

Respuesta :

mmm, you can work this one out in your head by reversing it. 
12.5 = 50g/4 
1/4 = 1/2 * 1/2 
thus in 14.4 seconds there have been 2 times the half life. 14.4/2 = 7.2 
the half life is 7.2 seconds.