AP Chemistry Practice questions with correct answers

If matter is uniform throughout and cannot be separated into other substances by physical means, it is ___. CORRECT ANSWER either an element or a compound Which of the following are chemical processes? I) rusting of a nail II) freezing of water III) decomposition of water into hydrogen and oxygen gases IV) compression of oxygen gas CORRECT ANSWER I and III only ____ refers to how close a measured number is to the true value CORRECT ANSWER Accuracy Barium reacts with a polyatomic ion to form a compound with the general formula Ba3(X)2. What would be the most likely formula for the compound formed between sodium and the polyatomic ion X? CORRECT ANSWER Na3X The mass % of H in methane (CH4) is ___. CORRECT ANSWER 25.13 The reaction between strontium hydroxide and chloric acid produces ___. CORRECT ANSWER a molecular compound and a strong electrolyte Oxidation cannot occur without ___. CORRECT ANSWER reduction The delta E of a system that absorbs 12.4 J of heat and does 4.2 J of work on the surroundings is ___J. CORRECT ANSW