Respuesta :

cdrosss1214
After first half-life you will have 100/2=50g. After second half-life you will have 50/2=25g.
Kerbal27
25 grams. 

A half life is the amount of time it takes for an isotope to decay half of itself. 

So after one half life, there will be half of the original amount. 

100/2=50

After another half life, there will be half of that amount. 

50/2 = 25