The answer for this one is a
Sodium (NA)
the sodium atom is donating its 1 valence electron to the chlorine atom. This creates a sodium cation and a chlorine anion. Notice that the net charge of the resulting compound is 0.
Answer:
Approximately 0.39 g or 0.4 g if you're rounding up
Explanation:
15/3.82 = 3.92
Let's round that up to 4
That means 15 days is around 4 half lives
4 half lives means 1/16 of the original mass will be left
25/16 = 0.390625