CHM 2045 General Chemistry 1 Final
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download
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1. Which statement best describes the fundamental distinction between
an element and a compound in terms of their chemical composition
and properties?
A. An element contains two or more different types of atoms chemically
combined, whereas a compound contains only one type of atom.
B. An element consists of only one type of atom, whereas a compound
contains two or more elements chemically combined in fixed proportions.
C. An element can be separated into simpler substances by physical means,
whereas a compound cannot be separated by any means.
D. An element always exists as a monatomic substance, whereas every
compound exists as a diatomic molecule.
Rationale: An element contains atoms with the same atomic number,
while a compound consists of atoms of different elements chemically
bonded in definite ratios.
, 2. A sample has a mass of 48.6 g and occupies a volume of 18.0 mL. What
is the density of the sample, reported with the appropriate number of
significant figures?
A. 0.370 g/mL
B. 2.60 g/mL
C. 2.70 g/mL
D. 2.700 g/mL
Rationale: Density is calculated by dividing mass by volume: 48.6 g ÷ 18.0
mL = 2.70 g/mL. Three significant figures are appropriate because both
measured quantities have three significant figures.
3. Which measurement represents the greatest precision according to
the number of significant figures shown?
A. 5.2 g
B. 5.20 g
C. 5.200 g
D. 5.2000 g
Rationale: Precision in recorded measurements is reflected by the number
of significant figures and decimal-place resolution. The value 5.2000 g
records five significant figures and therefore indicates the finest stated
measurement resolution.
4. An atom contains 17 protons, 18 neutrons, and 17 electrons. Which
description correctly identifies this species?
A. An isotope of argon with a mass number of 35
B. A neutral chlorine-35 atom
,C. A chloride ion with a mass number of 34
D. A neutral sulfur-35 atom
Rationale: The atomic number is determined by the 17 protons, identifying
chlorine. The atom has 17 electrons, so it is neutral, and its mass number is
17 + 18 = 35.
5. Which statement correctly explains why isotopes of the same element
have similar chemical properties but different masses?
A. Isotopes have different numbers of protons but identical numbers of
neutrons.
B. Isotopes have the same number of protons and electrons in neutral
atoms but different numbers of neutrons.
C. Isotopes have different numbers of electrons and identical numbers of
neutrons.
D. Isotopes differ in both atomic number and chemical identity.
Rationale: Isotopes possess the same atomic number and therefore the
same electron configuration in neutral atoms, but they differ in neutron
number, producing different masses.
6. An element exists as two naturally occurring isotopes. Isotope X has a
mass of 10.01 amu and an abundance of 19.9%, while isotope Y has a
mass of 11.01 amu and an abundance of 80.1%. What is the
approximate average atomic mass?
A. 10.01 amu
B. 10.81 amu
C. 11.01 amu
D. 21.02 amu
, Rationale: The weighted average is (10.01 × 0.199) + (11.01 × 0.801) ≈
10.81 amu. Average atomic mass therefore depends on both isotope mass
and natural abundance.
7. Which electron configuration correctly represents a neutral oxygen
atom in its ground state?
A. 1s² 2s² 2p²
B. 1s² 2s² 2p⁴
C. 1s² 2s² 2p⁶
D. 1s² 2p⁶
Rationale: Oxygen has atomic number 8 and therefore has eight electrons.
Filling orbitals according to the Aufbau principle gives 1s² 2s² 2p⁴.
8. Which principle states that no two electrons in the same atom can
possess an identical set of four quantum numbers?
A. Aufbau principle
B. Hund's rule
C. Pauli exclusion principle
D. Heisenberg uncertainty principle
Rationale: The Pauli exclusion principle requires electrons occupying the
same orbital to have opposite spins because no two electrons can have the
same four quantum numbers.
9. Which electron arrangement for the three 2p orbitals is consistent
with Hund's rule for a carbon atom?
A. ↑↓ | — | —
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download
Pdf.
1. Which statement best describes the fundamental distinction between
an element and a compound in terms of their chemical composition
and properties?
A. An element contains two or more different types of atoms chemically
combined, whereas a compound contains only one type of atom.
B. An element consists of only one type of atom, whereas a compound
contains two or more elements chemically combined in fixed proportions.
C. An element can be separated into simpler substances by physical means,
whereas a compound cannot be separated by any means.
D. An element always exists as a monatomic substance, whereas every
compound exists as a diatomic molecule.
Rationale: An element contains atoms with the same atomic number,
while a compound consists of atoms of different elements chemically
bonded in definite ratios.
, 2. A sample has a mass of 48.6 g and occupies a volume of 18.0 mL. What
is the density of the sample, reported with the appropriate number of
significant figures?
A. 0.370 g/mL
B. 2.60 g/mL
C. 2.70 g/mL
D. 2.700 g/mL
Rationale: Density is calculated by dividing mass by volume: 48.6 g ÷ 18.0
mL = 2.70 g/mL. Three significant figures are appropriate because both
measured quantities have three significant figures.
3. Which measurement represents the greatest precision according to
the number of significant figures shown?
A. 5.2 g
B. 5.20 g
C. 5.200 g
D. 5.2000 g
Rationale: Precision in recorded measurements is reflected by the number
of significant figures and decimal-place resolution. The value 5.2000 g
records five significant figures and therefore indicates the finest stated
measurement resolution.
4. An atom contains 17 protons, 18 neutrons, and 17 electrons. Which
description correctly identifies this species?
A. An isotope of argon with a mass number of 35
B. A neutral chlorine-35 atom
,C. A chloride ion with a mass number of 34
D. A neutral sulfur-35 atom
Rationale: The atomic number is determined by the 17 protons, identifying
chlorine. The atom has 17 electrons, so it is neutral, and its mass number is
17 + 18 = 35.
5. Which statement correctly explains why isotopes of the same element
have similar chemical properties but different masses?
A. Isotopes have different numbers of protons but identical numbers of
neutrons.
B. Isotopes have the same number of protons and electrons in neutral
atoms but different numbers of neutrons.
C. Isotopes have different numbers of electrons and identical numbers of
neutrons.
D. Isotopes differ in both atomic number and chemical identity.
Rationale: Isotopes possess the same atomic number and therefore the
same electron configuration in neutral atoms, but they differ in neutron
number, producing different masses.
6. An element exists as two naturally occurring isotopes. Isotope X has a
mass of 10.01 amu and an abundance of 19.9%, while isotope Y has a
mass of 11.01 amu and an abundance of 80.1%. What is the
approximate average atomic mass?
A. 10.01 amu
B. 10.81 amu
C. 11.01 amu
D. 21.02 amu
, Rationale: The weighted average is (10.01 × 0.199) + (11.01 × 0.801) ≈
10.81 amu. Average atomic mass therefore depends on both isotope mass
and natural abundance.
7. Which electron configuration correctly represents a neutral oxygen
atom in its ground state?
A. 1s² 2s² 2p²
B. 1s² 2s² 2p⁴
C. 1s² 2s² 2p⁶
D. 1s² 2p⁶
Rationale: Oxygen has atomic number 8 and therefore has eight electrons.
Filling orbitals according to the Aufbau principle gives 1s² 2s² 2p⁴.
8. Which principle states that no two electrons in the same atom can
possess an identical set of four quantum numbers?
A. Aufbau principle
B. Hund's rule
C. Pauli exclusion principle
D. Heisenberg uncertainty principle
Rationale: The Pauli exclusion principle requires electrons occupying the
same orbital to have opposite spins because no two electrons can have the
same four quantum numbers.
9. Which electron arrangement for the three 2p orbitals is consistent
with Hund's rule for a carbon atom?
A. ↑↓ | — | —
