Chapter 9 Practice Test

Transcription

1 Chapter 9 Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1) Which of the following describes a chemical reaction? a) A gas is given off when a liquid boils. b) A solid forms when a liquid freezes. c) A new substance is formed with different properties. d) A solid dissolves in a liquid. 2) Which of the following is NOT a sign of a chemical reaction? a) gas formation b) solid formation c) energy change d) state change 3) Which of the following occurs when water freezes? a) a physical change b) a chemical reaction c) a chemical bond d) a diatomic bond 4) What is the force that holds two atoms together called? a) a chemical solution b) a chemical mixture c) a chemical reaction d) a chemical bond 5) How do substances form during a chemical reaction? a) Two or more substances are combined. b) Chemical bonds break; atoms rearrange; new chemical bonds form. c) A solid substance is formed in a solution. d) Chemical bonds in molecules add atoms to make more molecules. 6) A calcium carbonate molecule has 1 calcium (Ca) atom, 3 oxygen (O) atoms, and 1 carbon (C) atom. Which of the following shows the chemical formula for calcium carbonate? a) 3CaCO b) Ca 2 CO 2 c) CaCO 3 d) CaC 2 O 3 7) The symbol for iron is Fe. The chemical symbol for oxygen is O. The formula for iron oxide, a type of rust, is Fe 2 O 3. How many iron atoms are in one molecule of iron oxide? a) one b) two c) three d) four 8) What is the charge of an ionic compound? a) 0 b) +1 c) -1 d) +2 9) Which of the following is the product in the chemical equation N + O 2 NO 2? a) N b) O c) O 2 d) NO 2 10) Which of the following uses coefficients correctly to balance the equation N 2 + H 2 NH 3? a) N 2 + 3H 2 2NH 3 b) 2N 2 + 2H 2 4NH 3 c) N 2 + H 2 NH 3 d) 3N 2 + 4H 2 6NH 3 11) Which of the following states the law of conservation of mass? a) Atoms are rearranged in a reaction and join new molecules. b) Compounds 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.

2 12) Nitrogen dioxide is a covalent compound. How many oxygen atoms are in a nitrogen dioxide molecule? a) three b) two c) one d) none 13) How many oxygen atoms are present on the reactant side of the chemical equation 4Fe + 3O 2 2Fe 2 O 3? a) two b) three c) four d) six 14) What type of reaction occurs when chlorophyll breaks down into new substances? a) a physical reaction b) a chemical reaction c) a nuclear reaction d) an unbalanced reaction 15) Which of the following is true of the new substances formed in a chemical reaction? a) Their chemical and physical properties differ from those of the original substances. b) Their properties are the same as those of the original substances. c) Only their physical properties differ from those of the original materials. d) Only their chemical properties differ from those of the original materials. 16) Which of the following is a sign of a chemical reaction? a) steam on a skating rink b) ice melting on the ground c) a dissolving solid d) a solid precipitate 17) How can you be sure a chemical reaction is happening? a) A solid dissolves. b) A new substance is formed. c) Water turns to steam. d) A mixture is made. 18) When chemical bonds break, what do atoms do? a) change into other atoms b) become energy c) rearrange d) disappear 19) What does a prefix in a chemical formula represent? a) the number of atoms of each element b) the number of chemicals c) the number of molecules d) the number of elements 20) What happens to atoms in a chemical reaction? a) They are sometimes lost and never rearranged. b) They are sometimes lost, gained, or rearranged. c) They are never lost or gained, just rearranged. d) They are lost or gained, and never rearranged. 21) What must be done for a chemical equation to be balanced? a) All molecules must be counted. b) All chemicals must be equal. c) All atoms must be counted. d) All atoms must be discounted. 22) Which statement is true according to the law of conservation of energy? a) Energy can be created. b) Energy cannot be destroyed. c) Energy cannot be transferred. d) Energy cannot change forms. 23) What happens in an exothermic reaction? a) Energy is destroyed. b) Energy is released. c) Energy is created. d) Energy is taken in.

3 24) What happens in an endothermic reaction? a) Energy is destroyed. b) Energy is released. c) Energy is created. d) Energy is taken in. 25) Which statement is true according to the law of conservation of mass? a) Mass is destroyed. b) Mass is not created. c) The mass of the reactants is greater than the mass of the products. d) The mass of the products is greater than the mass of the reactants. 26) Which of the following is NOT an example of a chemical reaction? a) milk turning sour b) food being digested c) a match burning d) ice melting 27) For a chemical bond to break, a) individual atoms must be present. b) energy is required. c) covalent compounds must be mixed. d) solids must be dissolved. 28) A precipitate is usually a a) solid. b) gas. c) liquid. d) solution. 29) If a chemical symbol in a chemical formula has no subscript, it means a) there are no atoms in the molecule. b) the element has no charge. c) the chemical is listed last in the formula. d) only one atom of the element is in the molecule. 30) Which of the following is the chemical formula for a dinitrogen trioxide molecule? a) N 2 O 3 b) 3N 2 O c) 2N 3 O 2 d) NO 3 31) Why does the law of conservation of mass dictate that chemical equations be balanced? a) because atoms are never gained or lost in a chemical reaction b) because elements are classified by weight c) because chemical formulas are written from left to right d) because using the wrong chemical symbol causes confusion 32) Which of the following shows coefficients being used correctly to balance the equation? a) Na + Cl 2 2NaCl b) Na + 2Cl 2 2NaCl c) 2Na + Cl 2 2NaCl 2 d) 2Na + Cl 2 2NaCl 33) The law of conservation of energy states that energy cannot be created or a) changed. b) destroyed. c) transferred. d) developed. 34) What is O 2 an example of? a) chlorophyll b) a diatomic molecule c) a chemical bond d) an ion 35) In the equation C + O 2 CO 2, CO 2 is the a) coefficient. b) precipitate. c) reactant. d) product. 36) Which of the following are used to balance an equation? a) subscripts b) coefficients c) reactants d) products

4 37) How many atoms are represented in the formula CaCO 3? a) three b) four c) five d) six 38) Which of the following statements explains the law of conservation of energy? a) In a chemical reaction, energy is neither created nor destroyed, but can change in form. b) Energy is needed to break chemical bonds. c) Light energy is released by some exothermic reactions. d) An exothermic reaction releases energy. 39) Which of the following chemical reactions illustrates an endothermic reaction? a) CaCO 3 CaO + CO 2 b) 4H2 + 2O 2 2H 2 O c) 6CO 2 + 6H 2 O + energy C 6 H 12 O 6 + 6O 2 d) 4KI + 2Cl 2 4KCl + 2I2 40) Which of the following is proof that a chemical reaction has taken place? a) A solid forms in a liquid. b) The color of a liquid changes. c) A new substance with different properties is formed. d) A substance becomes noticeably warmer. 41) Which of the following chemical equations is balanced? a) 3Ca + O 2 3CaO 2 b) 3Ca + 2O 2 5CaO 2 c) Ca + 2O 2 2CaO 2 d) Ca + O 2 CaO 2 42) Which of the following is an example of a chemical reaction? a) ice melting in a glass of water b) paper turning soft when wet c) salt crystals forming as sea water evaporates d) leaves changing colors in the fall 43) Which of the following names a covalent compound? a) aluminum sulfate b) dinitrogen dioxide c) iron oxide d) sodium chloride 44) How many sodium atoms are represented in the formula 7Na 3PO 4? a) 3 b) 7 c) 21 d) 28 45) Which of the following is an example of chemical bonds breaking? a) An explosive breaks rocks in a mine. b) A person breaks rocks with a hammer c) Boiling water gives off steam. d) Low temperatures cause icicles to form.

5 Chapter 9 Test Answer Section MULTIPLE CHOICE 1) C 41) D 2) D 42) D 3) A 43) B 4) D 44) C 5) B 45) A 6) C 7) B 8) A 9) D 10) A 11) C 12) B 13) D 14) B 15) A 16) D 17) B 18) C 19) A 20) C 21) C 22) B 23) B 24) D 25) B 26) D 27) B 28) A 29) D 30) A 31) A 32) D 33) B 34) B 35) D 36) B 37) C 38) A 39) C 40) C