After the first 2 min the 20 g are only 10g, (1 half-life)
after other 2 more min 5g (2 half-lives)
after other 2 more min 2.5 g (3 half-lives)
after 2 more 1.25 g (4 haf lifes)
The inner core us the densest
+3
Hence, the magnetic behaviour of the complex is paramagnetic. The oxidation number of the central metal atom: The oxidation number of the metal iron is +3.
