Listed below are sets of elements. which group contains elements that have the following characteristics: 1) at least one is a metalloid. 2) at least one forms an ion with a charge of -2. 3) at least one is a gas. 4) at least one is a halogen. a) oxygen, fluorine, and aluminum b) chlorine, sulfur, and silicon c) arsenic, oxygen, neon, hydrogen d) silicon, magnesium, neon, iodine

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.