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

Answer:
Answer: (b) F
Explanation:
Sodium has 1, magnesium has 2 and Aluminium has 3 electrons in its outermost shell whereas Fluorine has 7 electrons in its outermost shell hence Fluorine does not lose electrons easily.
The electronic configuration of fluorine is 2,7.
Fluorine is the ninth element with a total of 9 electrons.
The first two electrons will go in the 1s orbital.
The next 2 electrons for F go in the 2s orbital.
The remaining five electrons will go in the 2p orbital. Therefore the F electron configuration will be 1s22s22p5.
Ok thanks wkwksnmenenenenenenwnwnnwnwnwnw
Answer:
it is the app for homework not for nonsense things.
do good be good and see good and think good