ACT SCIENCE VOCABULARY

Absolute zero CORRECT ANSWER Approximately -273° C; the lowest possible temperature Acid CORRECT ANSWER A compound that releases hydrogen ions when dissolved in water; has a pH of less than 7 Algae CORRECT ANSWER Simple, one-celled plantlike organism found in water or damp places; includes seaweeds, pond scum, and so on Alloy CORRECT ANSWER A substance composed of two or more metals Atmosphere CORRECT ANSWER The layer of air surrounding Earth Atmospheric pressure CORRECT ANSWER The pressure exerted by the atmosphere on every part of Earth's surface; approximately 10 newtons per square centimeter Atom CORRECT ANSWER The smallest part of an element that is recognizable as that element Barometer CORRECT ANSWER An instrument that measures atmospheric pressure Base CORRECT ANSWER A compound that releases hydroxide ions in water; has a pH of more than 7; is sometimes called an alkali Boiling point CORRECT ANSWER The temperature at which additional thermal energy causes a substance to change from a liquid to a vapor Calorie CORRECT ANSWER A quantity of heat energy; the amount needed to raise the temperature of one gram of water 1° C Carbohydrate CORRECT ANSWER An organic compound-like sugar or starch that contains carbon, hydrogen, and oxygen in the ratio of 1:2:1; the human body's main source of energy