48) Under conditions of limited oxygen, carbon burns to form carbon monoxide, a poisonous gas. In
conditions with unlimited oxygen, carbon burns to form carbon dioxide. This illustrates the Law of
A) Conservation of Mass.
B) Definite Proportions.
C) different chemical reactions.
D) Multiple Proportions.
49) In plentiful air, 3.0 parts of carbon react with 8.0 parts of oxygen to form carbon dioxide. How much
carbon is required to react with 1100 g of oxygen?
A) 600 g
B) 550 g
C) 2930g
D) 413 g
50) Which set of compounds illustrates the Law of Multiple Proportions?
A) SO2, SO3
B) N2O, NO, NO2
C) H2O, H2O2
D) all of these
51) John Dalton discovered which of the following laws?
A) The Law of Conservation of Mass
B) The Law of Definite Proportions
C) The Law of Constant Composition
D) The Law of Multiple Proportions
52) Atoms of the same element that have different masses are called
A) allotropes.
B) anions.
C) isotopes.
D) molecules.
53) Which of the following postulates of Dalton’s atomic theory has been modified in light of later
discoveries?
A) All matter is made up of very small particles called atoms.
B) All atoms of an element are identical.
C) Chemical reactions involve rearrangement of atoms.
D) Compounds are formed from atoms.
54) How many grams of carbon are in 20.0 grams of CH4?
A) 18.46 grams
B) 14.98 grams
C) 4.00 grams
D) 8.00 grams
55) One mole is of carbon is equal to
A) 6.022 × 1023 atoms of carbons.
B) 12.011 grams of carbon.
C) Avogadro’s number of atoms.
D) all of the above.
56) The atomic masses for elements are
A) actual masses determined by weighing individual atoms.
B) relative masses determined by comparison with a standard reference.
C) the same as the atomic number.
D) unknown.
57) Perhaps the greatest triumph of Mendeleev’s periodic table was
A) the use of rows and columns to organize the elements.
B) the ability to predict electron configurations of elements.
C) the use of atomic numbers as an organizing criterion.
D) the prediction of the existence of undiscovered elements.
58) The scientist who in 1828 published a table of atomic weights containing 54 elements was
A) Dalton.
B) Berzelius.
C) Mendeleev.
D) Boyle.
59) The Periodic Table is helpful in all of the following endeavors but one. Which is the exception?
A) predicting formulas of compounds
B) predicting chemical reactivity of elements
C) predicting physical properties of elements
D) predicting monetary values of elements
60) Mendeleev arranged elements in the periodic table primarily in order of their
A) atomic masses.
B) atomic weights.
C) both atomic weights and atomic numbers.
D) number of neutrons.
61) What is the name of the Russian chemist who was a pioneer in the development of the periodic law?
A) Meyerovic
B) Mendeleev
C) Döbereiner
D) Berzelius
62) When Mendeleev developed his periodic table, he placed the greatest emphasis on
A) the atomic number of the elements.
B) putting elements with similar properties in the same column.
C) leaving no holes or blank spaces in the table.
D) the melting points of the elements.
63) The “box” for an element on the periodic table will include all of the following information about an
element EXCEPT
A) its atomic number.
B) the proportion of the element in a compound.
C) its atomic symbol.
D) its atomic mass.
64) Mendeleev’s periodic table organized elements in a systematic way. Which of the following
attempted to arrange elements in a systematic way and can be considered a “precursor” of the modern
periodic table?
A) Dalton’s Atomic Theory
B) Dalton’s Atomic Masses
C) Döbereiner’s Triads
D) Berzelius’s Atomic Weights
65) In 1961, the reference for the atomic mass unit (amu or u) was changed from naturally occurring
oxygen with a value of 16.000 u to one based on a single isotope of carbon (carbon–12). Why was it
changed?
A) The atomic composition of oxygen varies depending upon its source.
B) Carbon-12 is more common than oxygen.
C) Carbon exists as only one isotope, carbon–12.
D) Carbon can combine with four atoms of hydrogen to form CH4, methane, while oxygen only combines
with two atoms of hydrogen to form water, H2O.
66) Assume that you have a new “triad” of elements (A, B and C) with similar properties. A is the
smallest element and has a mass of 30 u. C is the largest element and has a mass of 90 u. The mass of B
would be approximately ________ u.
A) 40
B) 45
C) 60
D) 80
67) Is it always possible to recycle and reuse materials?
A) Yes, because atoms cannot be destroyed in a chemical reaction.
B) Yes, because atoms can only be rearranged in a chemical reaction.
C) No, because atoms can be changed into other kinds of atoms.
D) No, if it is financially impractible to do it.
68) For which of the following would recycling of iron NOT be practical?
A) old cars that are compressed in junkyards
B) steel beams that have been removed from a bridge
C) rust that flakes off a car body
D) wrought iron fences
69) If drops of water are subdivided to the ultimately smallest drops possible, what is the smallest
particle of water that retains the chemical and physical properties of water?
A) molecule
B) mixture
C) atom
D) micron
70) All of the following are molecules EXCEPT ________.
A) H2
B) NO
C) H
D) O3
71) All of the following are examples of molecules EXCEPT ________.
A) Si
B) CO
C) I2
D) NO2
72) Which of the following changes is NOT an example of green chemistry?
A) replacing mercury thermometers with alcohol thermometers
B) using large amounts of solvents such as benzene, which is a carcinogen
C) replacing energy from coal-fired power plants with energy from alternative sources
D) replacing lead in paint with titanium dioxide
73) Which of the following is an example of green chemistry?
A) building new coal-fired plants to generate electricity
B) developing new technologies that require rare elements
C) using materials that are made up of substances that are very abundant in the earth’s crust
D) using lead as a plasticizer to make plastics less rigid
2.2 True/False Questions
1) Leucippus and Democritus based their ideas about atoms on careful experimental results.
2) Aristotle’s idea that matter is continuous is still considered to be correct.
3) Democritus thought that real substances were mixtures of various types of atoms.
4) During a chemical reaction, matter can neither be created nor destroyed.
5) Lavoisier’s experiments showed that matter can be gained or lost in a chemical change.
6) The Law of Constant Composition and the Law of Definite Proportions are different names for the
same phenomenon.
7) Substance A contains 80% carbon and 20% hydrogen. Substance B contains 83% carbon and 17%
hydrogen. A and B are the same substance.
8) Substance A contains 85% carbon and 15% hydrogen. Substance B contains 85 % carbon and 15%
hydrogen. A and B are the same substance.
9) Water and hydrogen peroxide are compounds composed of only hydrogen and oxygen. These
compounds illustrate the Law of Multiple Proportions.
10) Dalton’s atomic theory states that atoms may change into other atoms in a chemical reaction.
11) According to Dalton’s Atomic Theory, atoms of the same element may have different masses.
12) Mendeleev was the first person to attempt to arrange the elements in a systematic order.
13) Mendeleev arranged the elements in his periodic table solely in order of increasing atomic mass.
14) Döbereiner’s Triads and Mendeleev’s Periodic Table were both based on the idea that properties of
elements tended to repeat.
15) Germanium was discovered in 1886. Its existence had been predicted by Mendeleev.
16) Scientists can observe computer enhanced images of atoms.
22
17) A molecule is a group of atoms that are chemically bonded together.
18) We cannot destroy atoms. Thus, it is possible to reclaim and recycle all materials.
19) Recycling of hazardous materials is important.
20) There is no difference between the hazard posed by an element when it is in a compound or by itself.
2.3 Short Answer Questions
1) Antoine Lavoisier is often credited with doing more than anyone else to establish chemistry as a
quantitative science. What was the significance of Lavoisier’s work?
2) When 10.0 g of lead are heated with 1.6 g of sulfur, 11.6 g of lead sulfide are formed. How many grams
of lead sulfide form when 10.0 g of lead are heated with 3.0 g of sulfur?
3) Describe what happens in a chemical reaction.
4) In light of present day knowledge, comment on Dalton’s proposal that atoms are indivisible.
5) Explain why Mendeleev left gaps in his periodic table of the elements.
2.4 Essay Questions
1) What is the significance of the Law of Conservation of Mass in waste disposal?
2) Distinguish between a compound and a mixture.