You Marie Curie assistant and your task is to study a piece of material and 2 points track its decay. You are starting with a 10kg lump of an unknown material. After 5 days you measure it again and only have 7.5kg remaining of the original material, the other 2.5kg is now something else. Can you determine the half life? If so, what is the half life of this material? O 5 days O O 10 days © 15 days 20 days​