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 Carcinogen Correct Answer: A cancer-causing agent