Law of Conservation of Mass
  • 1. What are the coefficients that will balance this chemical equation?
A) 4, 3, 2
B) 2, 2, 1
C) 2, 1, 1
D) 3, 4, 2
  • 2. The illustrations show a conservation-of-mass experiment. The solution in the beaker lost mass because —
A) materials have less mass at high temperatures
B) some of the water molecules turned into gas
C) sodium sulfate (Na2SO4) is lighter than air
D) the mass of the reactants and products was less than 100 g
  • 3. In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following is illustrated by this activity?
A) The theory of covalent bonding
B) The law of conservation of momentum
C) The law of conservation of mass
D) The theory of thermal equilibrium
  • 4. What is the coefficient for H2O when the above equation is balanced?
A) 1
B) 3
C) 2
D) 4
  • 5. According to the law of conservation of mass, how much zinc was present in the zinc carbonate?
A) 40 g
B) 256 g
C) 88 g
D) 104 g
  • 6. The chemical equation shows CaCO3 being heated. Which of these statements best describes the mass of the products if 100 g of CaCO3 is heated?
A) The difference in the products’ masses is equal to the mass of the CaCO3.
B) The sum of the products’ masses is less than the mass of the CaCO3.
C) The mass of each product is equal to the mass of the CaCO3.
D) The sum of the products’ masses equals the mass of the CaCO3.
  • 7. Which chemical equation supports the law of conservation of mass?
A) Al4C3 (s) + H2O (l) 🡪 CH4 (g) + Al(OH)_3 (s)
B) CH4 (g) + 2O2 (g) 🡪 CO2 (g) + 2H2O (g)
C) 2H2O (l) 🡪 H2 (g) + O2 (g)
D) Zn (s) + HCl (aq) 🡪 ZnCl2 (aq) + H2 (g)
  • 8. When 127 g of copper reacts with 32 g of oxygen gas to form copper (II) oxide, no copper or oxygen is left over. How much copper (II) oxide is produced?
A) 32 g
B) 95 g
C) 127 g
D) 159 g
  • 9. When the above equation is balanced, the coefficient for magnesium chloride is —
A) 0
B) 3
C) 1
D) 2
  • 10. If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?
A) The products must have a different physical state than the reactants.
B) The density of the reactants must equal the density of the products.
C) The reactants must contain more complex molecules than the products do.
D) The total mass of the reactants must equal the total mass of the products.
  • 11. The mass of a rusty bicycle is found to be slightly greater than the mass of the same bicycle before it rusted. The change in mass indicates that the rusting process —
A) involves an energy-to-matter conversion
B) is a physical change
C) decreases the density of the metal
D) involves metal bonding with other atoms
  • 12. Aluminum metal and oxygen gas combine to produce aluminum oxide (Al2O3). Which of these is the balanced equation for this reaction?
A) 4Al + 3O2 🡪 2Al2O3
B) Al + O2 🡪 Al2O3
C) 2Al + 2O2 🡪 2Al2O3
D) 2Al + 3O2 🡪 5Al2O3
  • 13. When 39.5 g of isopropyl alcohol is added to 50 6 of water, what is the mass of the resulting mixture?
A) 10.5 g
B) 89.5 g
C) 50 g
D) 100 g
  • 14. Liquid 1 and Liquid 2 react to produce a solid and a gas. Which of the following expressions correctly shows how to determine the mass of the gas?
A) (mass of Liquid 1 - mass of Liquid 2) ÷ (mass of solid)
B) (mass of Liquid 1 + mass of Liquid 2) + (mass of solid)
C) (mass of Liquid 1 + mass of Liquid 2) - (mass of solid)
D) (mass of Liquid 1 × mass of Liquid 2) ÷ (mass of solid)
  • 15. Copper (Cu) and sulfur (S) were heated in a covered container. After the reaction was complete, the unreacted sulfur was removed. The table contains the results of the investigation. How much sulfur, in grams, failed to react with the copper?
A) 4.54 g
B) 1.32 g
C) 10.88 g
D) 5.02 g
  • 16. Which additional product balances this reaction?
A) 2H2O (g)
B) CH4 (g)
C) 4OH (aq)
D) H2O2 (g)
  • 17. Which set of coefficients balances the equation?
A) 6, 1, 1, 3
B) 3, 3, 1, 2
C) 6, 2, 1, 6
D) 3, 2, 1, 6
  • 18. Which of these would support the idea that mass is conserved in a reaction that produces a gas as a product?
A) Subtracting the mass of the gas from the mass of the solid and liquid products
B) Mixing the reactants and measuring their total mass
C) Heating the reactants to ensure the reaction occurs in a gaseous state
D) Trapping the gas and measuring its mass
  • 19. If 43.7 g of iron is completely used in the reaction above, how many grams of oxygen are involved in the reaction?
A) 106.2 g
B) 16.0 g
C) 1.43 g
D) 18.8 g
  • 20. Which diagram best demonstrates the law of conservation of mass?
A) a
B) b
C) d
D) c
  • 21. In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following conclusions can be based on this diagram?
A) The results are invalid because the rubber stopper was not removed.
B) The mass of the reactants is less than the mass of the products.
C) Mass is not conserved when matter changes its phase.
D) The mass of the products is equal to the mass of the original reactants.
  • 22. Which of the following statements accurately describes the reaction shown above?
A) The mass of the nitrogen and hydrogen gases is double the mass of ammonia.
B) The mass of the nitrogen and hydrogen gases is greater than the mass of ammonia.
C) The mass of the nitrogen and hydrogen gases is equal to the mass of ammonia.
D) The mass of the nitrogen and hydrogen gases is less than the mass of ammonia.
  • 23. According to the law of conservation of mass, how much mercury was present in the mercury (II) oxide?
A) 126.0 g
B) 60.0 g
C) 64.2 g
D) 55.8 g
  • 24. Which of the following substances correctly completes the chemical equation above according to the law of conservation of mass?
A) CuS2O4
B) CuSO4
C) 2CuSO2
D) CuSO3
  • 25. When the above equation is balanced, what would be the coefficient on methane gas?
A) 4
B) 2
C) 3
D) 1
  • 26. Which chemical equation is correctly balanced and accurately describes the reaction written? Calcium sulfate precipitates out of solution when aqueous solutions of sodium sulfate and calcium chloride react with one another.
A) Na2SO4 (aq) + CaCl2 (aq) 🡲 CaSO4 (s) + 2NaCl (aq)
B) Na2SO4 (aq) + CaCl2 (aq) 🡲 CaSO4 (s) + NaCl (aq)
C) CaSO4 (s) + 2NaCl (aq) 🡲 Na2SO4 (aq) + CaCl2 (aq)
D) CaSO4 (s) + NaCl (aq) 🡲 Na2SO4 (aq) + CaCl2 (aq)
  • 27. Which chemical equation is correctly balanced and accurately describes the reaction written? Lithium hydroxide neutralizes nitric acid to yield lithium nitrate and water.
A) 2LiOH + HNO3 🡪 2LiNO3 + H2O
B) LiNO3 + H2O 🡪 LiOH + HNO3
C) LiOH + HNO3 🡪 LiNO3 + H2O
D) LiNO3 + 2H2O 🡪 2LiOH + HNO3
  • 28. Which of the following is the balanced chemical equation for the reaction shown above?
A) Al + H2SO4 🡪 Al2(SO4)3 + H2
B) 2Al + H2SO4 🡪 Al2(SO4)_3 + H2
C) 2Al + 3H2SO4 🡪 Al2(SO4)_3 + H2
D) 2Al + 3H2SO4 🡪 Al2(SO4)_3 + 3H2
  • 29. What would be the product(s) of this reaction?
A) 6Mg + Al3O2
B) Mg3Al2 + 3O2
C) 2Mg3Al2O3
D) 3Mg + Al2O3
  • 30. Which of the following equations is balanced?
A) H2O + MgO 🡪 Mg(OH)_2
B) CH4 + Cl2 🡪 CH2Cl2 + HCl
C) H2SO4 + 2NaOH 🡪 Na2SO4 + H2O
D) Al(OH)_3 + H3PO4 🡪 AlPO4 + 2H2O
  • 31. When this equation is correctly balanced, the coefficient of the AlCl3 will be —
A) 1
B) 6
C) 2
D) 4
  • 32. Which of the following is a balanced equation?
A) H2 + 2Br2 🡪 2HBr
B) 2H2 + Br2 🡪 HBr
C) H2 + Br2 🡪 HBr
D) H2 + Br2 🡪 2HBr
  • 33. The coefficients of the correctly balanced equation for the reaction illustrated above are —
A) 2, 1, 2
B) 1, 1, 2
C) 1, 1, 1
D) 2, 2, 1
  • 34. Which of these sets of coefficients will balance this equation?
A) 9, 3, 3, 3
B) 3, 1, 3, 1
C) 3, 3, 2, 1
D) 1, 6, 1, 9
  • 35. A balanced chemical equation has equal numbers of atoms of each type on both sides of the equation. This illustrates the principle of —
A) conservation of energy
B) action and reaction
C) conservation of mass
D) natural selection
  • 36. Which set of coefficients will balance this equation?
A) 2, 6, 2, 3
B) 1, 3, 1, 1
C) 2, 3, 2, 6
D) 3, 6, 3, 2
  • 37. Which completes the chemical equation above?
A) O2
B) ClO2
C) O3
D) ClO
  • 38. The partial chemical equation above represents the formation of lead(II) chloride. What is the missing reactant?
A) PbO(s)
B) Pb(s)
C) PbCl4(s)
D) PbO2(s)
  • 39. The coefficients necessary to balance the equation correctly are —
A) a = 2, b = 1, c = 1, d = 2
B) a = 2, b = 2, c = 1, d = 1
C) a = 1, b = 2, c = 1, d = 2
D) a = 1, b = 1, c = 1, d = 1
  • 40. Which reaction is correctly balanced?
A) Fe + 2CuSO4 🡪 2FeSO4 + Cu
B) Fe + CuSO4 🡪FeSO4 + Cu
C) 2Fe CuSO4 🡪 2FeSO4 Cu
D) Fe4 + CuSO4 🡪 FeSO4 + Cu
  • 41. Which set of coefficients will balance this equation?
A) 3, 1, 1
B) 2, 6, 2
C) 3, 2, 3
D) 2, 3, 2
  • 42. What are the coefficients of the correctly balanced equation?
A) 0, 2, 2, 3
B) 1, 3, 2, 3
C) 2, 6, 4, 3
D) 1, 2, 2, 2
  • 43. Which of the following equations is balanced?
A) Na + Cl2 🡪 2NaCl
B) 2Na + Cl2 🡪 2NaCl
C) 2Na + Cl2 🡪 NaCl2
D) Na + 2Cl 🡪 2NaCl2
  • 44. When the above equation is balanced, what would be the coefficient on lithium nitride?
A) 1
B) 4
C) 2
D) 3
  • 45. When the above equation is balanced, the coefficient of the hydrochloric acid (HCl) will be —
A) 2
B) 3
C) 6
D) 4
  • 46. When the equation below is balanced, what is the coefficient for oxygen?
A) 3
B) 4
C) 8
D) 5
  • 47. Which product balances the chemical equation below?
A) Fe(NO3)_3 (aq)
B) FeCl(aq)
C) FeCl2 (aq)
D) FeNO3 (aq)
  • 48. What is the balanced coefficient ratio for the reaction shown above?
A) 2:1:2:2
B) 2:3:2:2
C) 1:1:1:1
D) 3:3:3:2
  • 49. In a single-displacement reaction, the chemical change shown above occurs. Which equation supports the law of conservation of mass?
A) w + x = 2(y + z)
B) x = z
C) w = y
D) w + x = y + z
  • 50. Iron reacts with oxygen in the air to form iron oxide. The unbalanced equation for this reaction is shown above. What are the coefficients when this equation is balanced?
A) 2, 2, 1
B) 4, 3, 2
C) 2, 3, 1
D) 4, 2, 2
  • 51. This claim is false because it —
A) contradicts the law of conservation of matter
B) ignores the strength of the theory of strings
C) violates the principle of constant composition
D) violates the rules of gravitational attraction
  • 52. What is the coefficient for CO when theequation above is balanced?
A) 2
B) 4
C) 3
D) 1
  • 53. Which of these equations is the balanced form of the equation shown above?
A) NaCl3 + Al 🡲 AlCl3 + Na
B) 3NaCl + 3Al 🡲 AlCl3 + 3Na
C) 3NaCl + Al 🡲 AlCl3 + Na
D) 3NaCl + Al 🡲 AlCl3 + 3Na
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