Can you identify the gas that makes up most of Earth’s atmosphere? If yes, you may be surprised to be among the minority in the United States, LiveScience.com reports. (Hint: It’s not oxygen.) But if you know which kind of radiation that sunscreen protects against, you’re in good company. The American public’s knowledge of basic science and technology varies widely, according to the results of a 13-question survey by the Pew Research Center and Smithsonian magazine. About 78 percent of the public know red blood cells carry oxygen to the body, whereas 83 percent know sunscreen protects the skin from harmful ultraviolet rays, the poll found…