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

A. Phase changing. When phase changes nothing chemically changes about the substance, its still the same thing.
Explanation:
Among the numerous types of organic compounds, four major categories are found in all living things carbohydrates, lipids, proteins and nucleic acids.
Noble Gas. Metals have 1 or 2 Valence Electrons. Halogens have 7 Valence Electrons. Semi-Metals can have different amounts.