1. What is the chemical formula for dinitrogen monoxide? A N O B NO C NO D N O 2. Which of the following is NOT a clue that a chemical reaction is occurring? F gas formation G precipitation of a solid H change in the size and shape of a solid J color change 3. Which of the following is NOT the result of a chemical change? A soured milk B rusted metal C ground flour D digested food 4. Sodium (Na) metal reacts with water (H O) to form sodium hydroxide (NaOH) and hydrogen (H ) gas. Why is this change a chemical change? F because water is involved in the reaction G because new substances are formed H because the metal disappears in the water J because the amount of matter changes 5. Which of the following states the law of conservation of mass? A Atoms are rearranged in a chemical reaction, and some join new molecules. B Two compounds combine to form a new compound with different properties. C Mass cannot be created or destroyed in a chemical reaction. D Energy is neither created nor destroyed in a chemical reaction. 6. The chemical formula for ethanol is C H O. How many total atoms are in 30 molecules of ethanol? 7. Calculate the total number of atoms in the molecule represented by the following chemical formula: Na 3PO 4 A 3 B 11 C 8 D 22 8. Which of the following equations is balanced? F 2Fe O Fe O G Al CuSO Al (SO ) + Cu H 3Mg(OH) 2HCl MgCl + H O J H CO H O + CO
9. Balancing a chemical equation so that the same number of atoms of each element is found in both the reactants and the products is an example of A activation energy. B the law of conservation of energy C the law of conservation of mass. D a double-displacement reaction. 10. Look at the equations above. Which statement about these equations is true? F Equation 1 shows an endothermic reaction, and Equation 2 shows an exothermic reaction. G Equation 1 shows an exothermic reaction, and Equation 2 shows an endothermic reaction. H Both equations show exothermic reactions. J Both equations show endothermic reactions. 11. What information about a substance does a chemical formula provide? A how many atoms of each element are in a molecule B each element that s present in the substance C the total number of atoms in a molecule of the substance D all of the above 12. What is the correct position for a subscript in a chemical formula? F to the right of the element symbol G to the left of the element symbol H to the right and below the element symbol J to the right and above the element symbol 13. How many atoms of each element are in the formula below? C 2H 5OH A 1 C, 5 H, 1 O B 2 C, 5 H, 1 OH C 2 C, 6 H, 1 O D 1 C, 3 H, 5 O 14. What conclusion can be made about the properties of compounds containing the same elements? F More than one compound cannot be made from the same elements. G The properties of all the compounds are the same. H The properties of all the compounds are similar. J The properties of all the compounds are different. 15. What is the significance of a chemical formula that has no subscripts? A This indicates a nonexistent substance. B All the elements are in a 0:0 ratio. C All the elements are in a 1:1 ratio. D All the elements are in an unknown ratio. 16. How many atoms are in a molecule of the compound CH 3COC 10H 6OH? F 8 G 3 H 24 J 25
17. One molecule of a compound contains one nitrogen atom and two oxygen atoms. What is the correct chemical formula for this compound? A NoO B O 2N C N 2O D NO 2 18. A change in a substance occurred that did not involve a change in the identity of the substance. What kind of change took place? F both a physical and a chemical change G neither a physical nor a chemical change H a physical change J a chemical change 19. Which one of the following does not always indicate that a chemical change has taken place? A a color change occurs B an odor is produced C a precipitate forms D a solid forms 20. What type of reaction produces a new substance from simpler substances? F decomposition G synthesis H combustion J burning 21. What type of reaction produces simpler substances, other than water and carbon dioxide, from a more complex one? A decomposition B synthesis C combustion D burning 22. What type of change takes place when water boils to produce steam? F decomposition G a chemical change H a physical change J no change occurs 23. Which of these is a chemical change? A melting a piece of wax B dissolving sugar in water C tearing a sheet of paper D burning a log 24. What names are given to the substances that take part in a chemical reaction and those that are the result of the reaction? F products, reactants G reactants, products H atoms, compounds J compounds, products
25. What reactant is always involved in a combustion reaction? A hydrogen B carbon C oxygen D methane 26. Which information is not necessary to write a balanced chemical equation? F the direction of the reaction G the reactants and products in the reaction H the masses of the reactants and products in the reaction J the atomic symbols and chemical formulas of the reactants and products 27. What does a subscript represent in a chemical formula? A the total number of atoms in a molecule B the number of atoms of an element in a molecule C the total number of grams of an element in a molecule D the number of grams of a substance 28. What does a coefficient represent in a chemical equation? F the number of units of a reactant or product G the number of grams of a reactant or product H the number of liters of a reactant or product J the number of atoms in a reactant or product 29. What happens to the total amount of mass involved in a chemical reaction? A The total amount of mass increases. B The total amount of mass decreases. C The total amount of mass increases or decreases. D The total amount of mass remains constant. 30. How does a balanced chemical equation show the conservation of mass? F The number of molecules on each side of the equation is the same. G The total of the coefficients on each side of the equation is the same. H The number of atoms of each element on both sides of the equation is the same. J The total of the subscripts on each side of the equation is the same. 31. Why can you change the coefficients to balance a chemical equation but not the subscripts? A Changing a coefficient changes the identity of a substance in a reaction. B Changing a coefficient does not change the number of atoms in the reaction. C Changing a subscript changes the number of atoms in the reaction. D Changing a subscript changes the identity of a substance in a reaction. 32. What is not true of the law of conservation of mass and chemical reactions? F The number of atoms in the reactants is the same as the number of atoms in the products. G Atoms are rearranged to produce new substances. H Atoms are not created. J Atoms are not destroyed.
33. How do you determine the number of atoms of each element if a chemical formula has both a coefficient and a subscript? A The number of atoms is equal to the subscript. B The number of atoms is equal to the coefficient. C The number of atoms is equal to the coefficient multiplied by the subscript. D The number of atoms is equal to the sum of the coefficient and the subscript. 34. How many atoms are represented in the formula CaCO? F three G four H five J six 35. Calculate the number of oxygen atoms of the molecule represented in the following formula: Al (SO ). 36. What is true of the new materials formed in a chemical reaction? F Properties differ from original materials. G All substances have original properties. H Properties are the same as original materials. J No substances have original properties. 37. Rusting is an example of a A physical property. B physical change. C chemical property. D chemical change. 38. A scientist carries out a reaction in a test tube. After the bubbling stops, she notices that the test tube is very warm. What might she conclude about the reaction? F The reaction happened very quickly. G The reaction is endothermic. H The reaction is exothermic. J No reaction took place. 39. Balancing a chemical equation so that the same number of atoms of each element is found in both the reactants and the products is an example of A activation energy. B the law of conservation of energy. C the law of conservation of mass. D a double-displacement reaction. 40. Which describes what happens to atoms in a chemical reaction? F sometimes lost, never rearranged G sometimes lost, gained, or rearranged H never lost or gained, just rearranged J lost or gained, never rearranged
41. Which of the following equations is balanced? A Na + Cl B 2Na + Cl C Mg + N D 3Mg + 2N NaCl 2NaCl Mg N Mg N 42. Find the coefficients that will balance the following reaction. Record the numbers from left to right. If the coefficient is 1, write that. Al + CuSO Al (SO ) + Cu H 2 + O 2 2H 2 O 1. In the equation above, what is the subscript of the hydrogen molecule? a. 1 b. 2 c. 3 d. 0 2. All equations must be balanced. This means that the same number of atoms of each of the elements must be found in both the reactants and the products of the reaction. Which scientific law does this illustrate? a. Law of Conservation of Mass b. Law of Superposition c. Law of Conservation of Energy d. Law of Reflection 3. What does the arrow in the equation mean? a. Turns into b. Creates c. Yields d. Equals 4. Which of the following is a true statement? a. In a chemical equation, you can end up with a different number of atoms of an element on the reactant side for the same element on the product side. b. In a chemical equation, an element or compound must be accompanied by a phase change. c. In a chemical equation, the reactants and products can have different numbers of atoms for each element. d. In a chemical equation, the coefficients tell you the number of molecules of each reactant used and the number of molecules of each product made. 5. Which of the following is a true statement? I. Subscripts are used to identify substances II. Coefficients are used to identify substances III. Chemical formulas are used to identify substances IV. The elements and the number of atoms of each element present in a chemical formula are used to identify substances a. I and II b. III and IV c. I and III d. II and III