Why do scientists study deuterium to determine the origins of water on earth? a. deuterium only comes from outside the planet. b. deuterium reacts with oxygen to form water just like hydrogen does. c. deuterium has a neutron in its nucleus, whereas hydrogen does not. d. deuterium is easier to study than ordinary hydrogen.

Match the following items. 1. queen isabella of spain paid for him to sail west to reach the far east equator 2. largest ocean hemisphere 3. ocean around the north pole mir 4. russian space station vasco da gama 5. imaginary line around the middle of the earth pacific 6. first to sail from portugal, around africa, to india arctic 7. florida, a piece of land almost surrounded by water spice islands 8. an imaginary line through the earth around which the earth turns columbus 9. half of sphere peninsula 10. europeans 500 years ago wanted to find an all-water route to this place axis