Two colleagues gave blood for an emergency. Ned got infected with HIV because they re-used a needle. His friend Nate was not infected. Which colleague didn't have a virus that originated in sub-Saharan Africa?
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Answer: Nate

Mike has to learn more about the periodic table for his chemistry exam. To make things easier for him he chose two elements from the table, element A and element B. Element A has higher electronegativity and element B has lower eletronegativity. David found it easier to learn about elements by comparing their properties. Where element B most likely be across the column, up or down?
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Answer: down

The ozone layer helps organisms by protecting them from Sun's ultraviolet radiation. To find the usefulness of ozone layer Mike wanted to see how much ozone are there in the atmosphere. He then collected three samples of atmosphere, sample A sample B, and sample C. Sample A was collected from the upper portion of the stratosphere. Sample B was collected from the lower portion of the stratosphere. Sample C was collected from the lower atmosphere. Which sample's layer would protect less from ultraviolet radiation, sample A or sample B?
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Answer:
sample A