Chapter 03 - Stoichiometry
1. Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains
a. 79 protons, 79 electrons, and 35 neutrons. b. 35 protons, 44 neutrons, and 35 electrons. c. 44 protons, 44 electrons, and 35 neutrons. d. 34 protons and 35 ...
,Chapter 02 - Atoms, Molecules, and Ions
1. According to the law of definite proportions,
a. the ratio of the masses of the elements in a compound is always the same.
b. it is not possible for the same two elements to form more than one compound.
c. if the same two elements form two different compounds, they do so in the same ratio.
d. the total mass after a chemical change is the same as before the change.
ANSWER: a
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.2
KEYWORDS: compound | general chemistry | general concepts | matter
2. Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?
a. CaO and CaCl2
b. NO and NO2
c. H2S and HBr
d. SiH4 and SiO2
e. NF3 and NCl3
ANSWER: b
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.2
KEYWORDS: compound | general chemistry | general concepts | matter
3. How many of the following did Dalton not discuss in his atomic theory?
I. isotopes
II. ions
III. protons
IV. neutrons
V. electrons
a. 2
b. 5
c. 4
d. 1
e. 3
ANSWER: b
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.3
KEYWORDS: atomic theory of matter | Dalton's atomic theory | early atomic theory | general chemistry
4. When 2.0 L of oxygen gas (O2) reacts with 1.0 L of nitrogen gas (N2), 2.0 L of gaseous product is formed.
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,Chapter 02 - Atoms, Molecules, and Ions
All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?
a. NO
b. NO4
c. N2O3
d. N2O
e. NO2
ANSWER: e
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.4
KEYWORDS: chemical formula | chemical substance | early atomic theory | general chemistry | molecular
substance
5. Which one of the following statements about atomic structure is false?
a. Almost all of the mass of the atom is concentrated in the nucleus.
b. The protons and neutrons in the nucleus are very tightly packed.
c. The number of protons and the number of neutrons are always the same in the neutral atom.
d. The electrons occupy a very large volume compared to the nucleus.
ANSWER: c
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.4
2.5
KEYWORDS: atomic theory of matter | early atomic theory | general chemistry | nuclear structure
6. Which of the experiments listed below did not provide the information stated about the nature of the atom?
a. The Rutherford experiment proved that the Thomson "plum pudding" model of the atom was
essentially correct.
b. The Rutherford experiment determined the charge on the nucleus.
c. The cathode-ray tube proved that electrons have a negative charge.
d. Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the
charge on the electron.
ANSWER: a
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.5
KEYWORDS: atomic theory of matter | early atomic theory | general chemistry | structure of the atom
7. Which of the following atomic symbols is incorrect?
a. 3115P
b. 199F
Copyright Cengage Learning. Powered by Cognero. Page 2
, Chapter 02 - Atoms, Molecules, and Ions
c. 34
17Cl
d. 39
19K
e. 15
8C
ANSWER: e
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.5
KEYWORDS: atomic theory of matter | early atomic theory | general chemistry | isotope
8. The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its
nucleus
a. 75 protons, 110 neutrons.
b. 75 protons, 75 neutrons.
c. 75 protons, 130 neutrons.
d. 130 protons, 75 neutrons.
e. not enough information is given.
ANSWER: a
POINTS: 1
DIFFICULTY: easy
TOPICS: 2.5
KEYWORDS: atomic theory of matter | early atomic theory | general chemistry | isotope
9. Which of the following statements is(are) true?
I. O and F have the same number of neutrons.
C and N are isotopes of each other because their mass numbers are
II.
the same.
III. O2– has the same number of electrons as Ne.
a. I only
b. II only
c. III only
d. I and II only
e. I and III only
ANSWER: c
POINTS: 1
DIFFICULTY: moderate
TOPICS: 2.5
KEYWORDS: atomic theory of matter | early atomic theory | general chemistry | isotope
10. Which among the following represent a set of isotopes? Atomic nuclei containing
I. 20 protons and 20 neutrons.
II. 21 protons and 19 neutrons.
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