Sodium-25 after 3 minutes : 1.0625 mg
<h3>Further explanation</h3>General formulas used in decay:
T = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
<h3 />No=8 mg
t1/2=60 s
T=3 min=180 s