In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule contains two sets of double bonds. Two sets of double bonds means that the total number of electrons being shared in the molecule is (a) 2. (b) four. (c) 6. (d) 8

If a small-diameter open glass tube is partially immersed in a vessel containing mercury, the surface of the mercury inside the tube will be a. lower than the mercury in the vessel, and shaped like the inside of a bowl. b. higher than the mercury in the vessel, and shaped like the inside of a bowl. c. lower than the mercury in the vessel, and shaped like the outside of an umbrella. d. higher than the mercury in the vessel, and shaped like the outside of an umbrella.