Originalmass2n = Residual mass
Where n = number of activity = exposuretimehalflife
Given:
Original mass = 1g, exposure time = 10 minutes , half life = 2 minutes, Residual mass = ?
Substituting all the given parameters appropriately, we have
n = 102
n = 5
125 = Residual mass
132 = Residual mass
Residual mass = 132 or 0.03125g
