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Are you scientifically literate? Take our quiz

( of 50 correct)

1. Composing about 78 percent of the air at sea level, what is the most common gas in the Earth's atmosphere?

William & Mary professor Elizabeth Harbron displays vials with merocyanine and rhodamine dye in her lab in Williamsburg, Va. (Steve Helber/AP)


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Pastor Jean Enock Joseph (c.) visits one of his projects in Croix-des-Bouquets, just outside Port-au-Prince, Haiti’s capital.

Jean Enock Joseph teaches self-help to lift Haiti

Pastor Jean Enock Joseph doesn't shy from Haiti's toughest problems. His message: Haitians have the ability to help themselves.