Answer: Radon
Explanation: Radium is a decay product of Uranium. As Radium is still highly radioactive it further decays into Radon.
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Answer: crossing over
during the process of fertilization, a sperm and egg join together to create a zygote. since a sperm had half the number of chromosomes and an egg has half the number of chromosomes, when they join together the zygote had a complete diploid set of chromosomes. the assortment of chromosomes and crossing over promotes genetic variation during the process of reproduction
