Chapter 3 Practice Test

____ 1. If each atom of element D has 3 mass units and each atom of element E has 5 mass units, a chemical molecule composed of one atom each of D and E has

a.	15 mass units.	c.	35 mass units.
b.	2 mass units.	d.	8 mass units.

____ 2. A certain compound is composed of elements G and H. It always has the same mass ratio of G to H because

a.	all atoms have the same mass.	c.	G and H have characteristic masses.
b.	any excess of G or H will be destroyed.	d.	G and H have identical masses.

____ 3. If 6 g of element K combine with 17 g of element L, how many grams of element K combine with 85 g of element L?

a.	17 g	c.	30 g
b.	23 g	d.	91 g

____ 4. In oxides of nitrogen, such as N₂O, NO, NO₂, and N₂O₃, atoms combine in small whole-number ratios. This evidence supports the law of

a.	conservation of mass.	c.	definite composition.
b.	multiple proportions.	d.	mass action.

____ 5. Which two compounds are examples of the law of multiple proportions?

a.	FeCl3 and Fe2(SO4)3	c.	CO and CO2
b.	O2 and O3	d.	FeCl2 and Fe(NO3)2

____ 6. The law of multiple proportions can be partly explained by the idea that

a.	elements can combine in only one way to form compounds.
b.	whole atoms of the same elements combine to form compounds.
c.	elements in a compound always occur in a 1:1 ratio.
d.	only atoms of the same element can combine.

____ 7. If 3 g of element C combine with 8 g of element D to form compound CD, how many grams of D are needed to form compound CD2?

a.	8 g	c.	11 g
b.	16 g	d.	19 g

____ 8. Oxygen can combine with carbon to form two compounds, carbon monoxide and carbon dioxide. The ratio of the masses of oxygen that combine with a given mass of carbon is 1:2. This is an example of

a.	the law of conservation of mass.	c.	the law of conservation of energy.
b.	Dalton's atomic theory.	d.	the law of multiple proportions.

____ 9. If 63.5 g of copper (Cu) combine with 16 g of oxygen (O) to form the compound CuO, how many grams of oxygen will be needed to combine with the same amount of copper to form the compound CuO₂?

a.	16 g	c.	64 g
b.	32 g	d.	127 g

____ 10. According to the law of definite proportions, any two samples of KCl have

a.	the same mass.	c.	the same melting point.
b.	slightly different molecular structures.	d.	the same ratio of elements.

____ 11. The atomic mass of an atom of carbon is 12, and the atomic mass of an atom of oxygen is 16. To produce CO, 16 g of oxygen can be combined with 12 g of carbon. What is the ratio of oxygen to carbon when 32 g of oxygen combine with 12 g of carbon?

a.	1:1	c.	1:2
b.	2:1	d.	8:3

____ 12. Who was the schoolmaster who studied chemistry and proposed an atomic theory?

a.	John Dalton	c.	Robert Brown
b.	Jons Berzelius	d.	Dmitri Mendeleev

____ 13. Who first recognized that the ratio of the number of atoms that combine is the same as the ratio of the masses that combine?

a.	Jons Berzelius	c.	John Dalton
b.	Edward Morley	d.	Jon Newlands

____ 14. According to Dalton's atomic theory, atoms

a.	of different elements combine in simple whole-number ratios to form compounds.
b.	can be divided into protons, neutrons, and electrons.
c.	of all elements are identical in size and mass.
d.	can be destroyed in chemical reactions.

____ 15. The law of definite proportions

a.	contradicted Dalton's atomic theory.
b.	was explained by Dalton's atomic theory.
c.	replaced the law of conservation of mass.
d.	assumes that atoms of all elements are identical.

____ 16. Who proposed the law of multiple proportions?

a.	Avogadro	c.	Dalton
b.	Rutherford	d.	Thomson

____ 17. Which of the following statements is true?

a.	Atoms of the same element may have different masses.
b.	Atoms may be divided in ordinary chemical reactions.
c.	Atoms can never combine with any other atoms.
d.	Matter is composed of large particles called atoms.

____ 18. The atomic theory proposed by Dalton

a.	has been totally discarded.
b.	has been expanded and modified.
c.	has been accepted unchanged to the present day.
d.	has been found to be false.

____ 19. In a glass tube, electrical current passes from the negative electrode, called the ____, to the other electrode.

a.	cathode	c.	electron
b.	anode	d.	millikan

____ 20. The behavior of cathode rays produced in a glass tube containing gas at low pressure led scientists to conclude that the rays

a.	were not composed of matter.
b.	were composed of positively charged particles.
c.	were composed of negatively charged particles.
d.	were composed of uncharged particles.

____ 21. The discovery of the electron resulted from experiments using

a.	gold foil.	c.	neutrons.
b.	cathode rays.	d.	alpha particles.

____ 22. The deflection of cathode rays in Thomson's experiments was evidence of the ____ nature of electrons.

a.	wave	c.	particle
b.	charged	d.	spinning

____ 23. Who discovered the nucleus by bombarding gold foil with positively charged particles and noting that some particles were widely deflected?

a.	Rutherford	c.	Chadwick
b.	Dalton	d.	Bohr

____ 24. In Rutherford's experiments, very few positively charged particles

a.	were slightly deflected as they passed through the metal.
b.	were greatly deflected back from the metal.
c.	passed straight through the metal.
d.	combined with the metal.

____ 25. In Rutherford's experiments, positively charged particles

a.	passed through a tube containing gas.	c.	collided with electrons.
b.	were used to bombard a cathode plate.	d.	were used to bombard thin metal foil.

____ 26. In Rutherford's experiments, most of the particles

a.	bounced back.	c.	were absorbed by the foil.
b.	passed through the foil.	d.	combined with the foil.

____ 27. Rutherford's experiments led to the discovery of the

a.	electron.	c.	nucleus.
b.	cathode ray.	d.	neutron.

____ 28. Rutherford fired positively charged particles at metal foil and concluded that most of the mass of an atom was

a.	in the electrons.	c.	evenly spread throughout the atom.
b.	concentrated in the nucleus.	d.	in rings around the atom.

____ 29. In Rutherford's experiments, the backward deflection of alpha particles gave evidence of an atom's

a.	size.	c.	charge.
b.	electron orbitals.	d.	nucleus.

____ 30. The mass of a neutron is

a.	about the same as that of a proton.	c.	double that of a proton.
b.	about the same as that of an electron.	d.	double that of an electron.

____ 31. The nucleus of most atoms is composed of

a.	tightly packed protons.	c.	tightly packed protons and neutrons.
b.	tightly packed neutrons.	d.	loosely connected protons and electrons.

____ 32. Protons and neutrons strongly attract when they

a.	are moving fast.	c.	are at high energies.
b.	are very close together.	d.	have opposite charges.

____ 33. Protons within a nucleus are attracted to each other by

a.	nuclear forces.	c.	their energy levels.
b.	opposite charges.	d.	electron repulsion.

____ 34. Protons have

a.	negative charges.	c.	no charges.
b.	an attraction for neutrons.	d.	no mass.

____ 35. The forces that hold the particles in the nucleus together are called

a.	nuclear forces.	c.	magnetic forces.
b.	gravitational forces.	d.	electron clouds.

____ 36. The radius of an atom extends to the outer edge of the

a.	nucleus.	c.	region occupied by the neutrons.
b.	region occupied by the electrons.	d.	positive charges.

____ 37. Isotopes are atoms of the same element that have different

a.	principal chemical properties.	c.	numbers of protons.
b.	masses.	d.	numbers of electrons.
	NUMBERS 38-45 ARE NOT COVERED ON EXAM. THEY ARE FOR YOUR INFORMATION ONLY

____ 38. The only radioactive form of hydrogen is

a.	protium.	c.	tritium.
b.	deuterium.	d.	quadrium.

____ 39. The tritium atom consists of

a.	one proton, two neutrons, and two electrons.
b.	one proton, one neutron, and one electron.
c.	one proton, two neutrons, and one electron.
d.	two protons, one neutron, and one electron.

____ 40. What is the mass number of deuterium?

a.	1	c.	3
b.	2	d.	4

____ 41. How many isotopes of hydrogen are known?

a.	2	c.	4
b.	3	d.	5

____ 42. The hydrogen isotope with the least mass is named

a.	tritium.	c.	deuterium.
b.	helium.	d.	protium.

____ 43. Deuterium contains one proton and

a.	two neutrons.	c.	no neutrons.
b.	one neutron.	d.	two electrons.

____ 44. Deuterium differs from tritium in having one

a.	less neutron.	c.	more electron.
b.	more proton.	d.	more neutron.

____ 45. Protium contains one proton and

a.	one neutron.	c.	no neutrons.
b.	two neutrons.	d.	three electrons.

____ 46. Isotopes of each element differ in

a.	the number of neutrons in the nucleus.
b.	atomic number.
c.	the number of electrons in the highest energy level.
d.	the total number of electrons.

____ 47. In determining atomic mass units, the standard is the

a.	C-12 atom.	c.	H-1 atom.
b.	C-14 atom.	d.	O-16 atom.

____ 48. The atomic mass listed in the periodic table is the

a.	average atomic mass.
b.	relative atomic mass of the most abundant isotope.
c.	relative atomic mass of the most stable radioactive isotope.
d.	mass number of the most abundant isotope.

____ 49. An aluminum isotope consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is

a.	13.	c.	27.
b.	14.	d.	40.

____ 50. What is the atomic number for aluminum from the figure above?

a.	13	c.	26.98
b.	14	d.	26.9815

____ 51. A neutral carbon atom (atomic number 6) has

a.	3 electrons and 3 neutrons.	c.	3 protons and 3 electrons.
b.	6 protons.	d.	3 protons and 3 neutrons.

____ 52. Nickel-60 (atomic number 28) has

a.	28 neutrons.	c.	60 neutrons.
b.	32 neutrons.	d.	88 neutrons.

____ 53. Carbon-14 (atomic number 6), the radioactive nuclide used in dating fossils, has

a.	6 neutrons.	c.	10 neutrons.
b.	8 neutrons.	d.	14 neutrons.

____ 54. Sulphur-34 (atomic number 16) contains

a.	34 protons.	c.	18 neutrons.
b.	18 protons.	d.	16 neutrons.

____ 55. Silicon-30 contains 14 protons. It also contains

a.	16 electrons.	c.	30 neutrons.
b.	16 neutrons.	d.	44 neutrons.

____ 56. Neon-22 contains 12 neutrons. It also contains

a.	12 protons.	c.	22 electrons.
b.	22 protons.	d.	10 protons.

____ 57. Calcium-48 (atomic number 20) contains

a.	20 electrons.	c.	20 neutrons.
b.	48 protons.	d.	28 protons.

____ 58. Argon (atomic number 18 and mass number 40) has ____ protons in its nucleus.

a.	22	c.	40
b.	9	d.	18

____ 59. To determine the molar mass of an element, one must know the element's

a.	Avogadro constant.	c.	number of isotopes.
b.	atomic number.	d.	average atomic mass.

____ 60. If samples of two different elements each represent one mole, then

a.	they are equal in mass.	c.	their molar masses are equal.
b.	they contain the same number of atoms.	d.	they have the same atomic mass.

____ 61. The mass of two moles of oxygen atoms (atomic mass 16 amu) is

a.	16 g.	c.	48 g.
b.	32 g.	d.	64 g.

____ 62. The mass of a sample containing 3.5 mol of silicon atoms (atomic mass 28.0855 amu) is

a.	28 g.	c.	72 g.
b.	35 g.	d.	98 g.

____ 63. What is the number of moles of chemical units represented by 9.03 ´ 10²⁴ units?

a.	1.50 mol	c.	10.0 mol
b.	9.03 mol	d.	15.0 mol

____ 64. The mass of 2.50 mol of calcium atoms (atomic mass 40.08 amu) is approximately

a.	10.0 g.	c.	100 g.
b.	42.5 g.	d.	250 g.

____ 65. How many moles of atoms are in 50.15 g of mercury (atomic mass 200.59 amu)?

a.	0.1001 mol	c.	0.2500 mol
b.	0.1504 mol	d.	0.4000 mol

____ 66. A prospector finds 39.39 g of gold (atomic mass 196.9665 amu). She has

a.	1.20 ´ 10^23 atoms.	c.	4.30 ´ 10^23 atoms.
b.	2.30 ´ 10^23 atoms.	d.	6.02 ´ 10^23 atoms.

____ 67. A sample of tin (atomic mass 118.69 amu) contains 3.01 ´ 10²³ atoms. The mass of the sample is

a.	3.01 g.	c.	72.6 g.
b.	59.3 g.	d.	11 g.

____ 68. The mass of a sample of nickel (atomic mass 58.69 amu) is 176.07 g. It contains

a.	1.7607 ´ 10^24 atoms.	c.	5.869 ´ 10^23 atoms.
b.	1.806 ´ 10^24 atoms.	d.	5.869 ´ 10^24 atoms.

____ 69. The mass of a sample of nickel (atomic mass 58.69 amu) is 11.74 g. It contains

a.	1.174 ´ 10^23 atoms.	c.	1.869 ´ 10^23 atoms.
b.	1.205 ´ 10^23 atoms.	d.	3.256 ´ 10^23 atoms.

____ 70. The mass of exactly 5 mol of cesium (atomic mass 132.9 amu) is

a.	664.5 g.	c.	6.02 ´ 10^23 g.
b.	132.9 g.	d.	5 g.

Short Answer

71. How has Dalton's theory about atomic particles been modified by modern science?

72. What is the relationship between isotopes, mass number, and neutrons?

Problem

73. How many atoms are present in 80.0 mol of zirconium?

74. How many moles of iron are equivalent to 1.11 ´ 10²⁵ atoms?

75. Determine the mass in grams of 10.0 mol of bromine. The molar mass of bromine is 79.90 g/mol.

76. Calculate the number of atoms in 10.0 g of sulfur (molar mass 32.07 g/mol).

Essay

77. Explain what is meant by the law of definite proportions, the law of conservation of mass, and the law of multiple proportions.

78. What can you determine about the atomic structure of an element and one of its isotopes if you know the atomic number and mass numbers?

Chapter 3 Practice Test

Answer Section

MULTIPLE CHOICE

1. D

2. C

3. C

4. B

5. C

6. B

7. B

8. D

9. B

10. D

11. B

12. A

13. C

14. A

15. B

16. C

17. A

18. B

19. A

20. C

21. B

22. B

23. A

24. B

25. D

26. B

27. C

28. B

29. D

30. A

31. C

32. B

33. A

34. B

35. A

36. B

37. B

38. C-NOT ON TEST

39. C-NOT ON TEST

40. B-NOT ON TEST

41. B-NOT ON TEST

42. D-NOT ON TEST

43. B-NOT ON TEST

44. A-NOT ON TEST

45. C-NOT ON TEST

46. A

47. A

48. A

49. C

50. A

51. B

52. B

53. B

54. C

55. B

56. D

57. A

58. D

59. D

60. B

61. B

62. D

63. D

64. C

65. C

66. A

67. B

68. B

69. B

70. A

SHORT ANSWER

71. The discovery of subatomic particles proved that atoms are divisible. Dalton believed that atoms were indivisible.

72. Isotopes are atoms of the same element with different numbers of neutrons and therefore different mass numbers.

PROBLEM

73.

4.82 ´ 10²⁵ atoms Zr

74.

18.4 mol Fe

75.

799 g Br

76.

1.88 ´ 10²³ atoms S

ESSAY

77. Definite proportions: regardless of the origin or size of samples of a particular compound, their elements are always in the same proportion. Conservation of mass: the mass of the elements combined in a compound is the same as the sum of the masses of the individual elements. Multiple proportions: when two elements combine to form two different compounds, the ratio of the masses of one element that combine with a fixed mass of the other element is a small whole number.

78. The atomic number equals the number of protons in the nucleus of an atom and also equals the number of electrons in the neutral atom. The mass number is the sum of the number of protons and neutrons and can be used, with the atomic number, to find the number of neutrons. An isotope of an element has a different mass number but the same atomic number as the element.