Consider the following information:
i. The layer of dead skin on our bodies is sufficient to protect us from most α -particle radiation.
ii. Plutonium is an α-particle producer.
iii. The chemistry of Pu⁴⁺ is similar to that of Fe³⁺.
iv. Pu oxidizes readily to Pu⁴⁺. Why is plutonium one of the most toxic substances known?