CHEM 103 Combined Lecture Notes –
Complete Study Guide with Solutions
| 2026 Update:Solved Questions with
Detailed Rationales for General
Chemistry I Exam Success
1. Which property of matter can be observed without changing its
chemical identity?
Answer: Boiling point
Rationale: Physical properties are observable without altering
chemical composition. Flammability, reactivity with acid, and toxicity
involve chemical reactions .
2. How many significant figures are in the measurement 0.003050 m?
Answer: 4
Rationale: Leading zeros are not significant. Digits 3, 0, 5, 0 include
captive zeros and trailing zeros after a decimal, which are significant .
3. Convert 4.58 × 10³ cm³ to m³.
Answer: 4.58 × 10⁻³ m³
Rationale: Using the conversion factor 10⁶ cm³ = 1 m³: (4.58 × 10³) /
10⁶ = 4.58 × 10⁻³ .
,4. A student measures a beaker three times: 25.45 g, 25.46 g, 25.44 g.
The known mass is 25.50 g. The measurements are:
Answer: Precise but not accurate
Rationale: Measurements are close to each other (precise) but differ
from the true value (not accurate) .
5. Dimensional analysis is used to convert units. Which statement is
true?
Answer: Conversion factors are ratios of equivalent quantities
measured in different units
Rationale: Dimensional analysis uses conversion factors as ratios of
equivalent quantities. Units are set up to cancel, leaving the desired
unit .
6. The mass number of an atom is equal to:
Answer: The sum of protons and neutrons
Rationale: Mass number (A) is the total number of protons and
neutrons in the nucleus. Atomic number (Z) is the number of protons .
7. Which of the following is TRUE about isotopes?
Answer: Isotopes have the same number of protons but different
numbers of neutrons
Rationale: Isotopes have the same atomic number (same protons) but
different neutrons. They may be stable or radioactive .
8. The Bohr model of the atom describes electrons in:
Answer: Fixed orbits around the nucleus
Rationale: The Bohr model describes electrons in fixed orbits around
the nucleus .
, 9. Which subatomic particle has a positive charge and is located in the
nucleus?
Answer: Proton
Rationale: The proton carries a +1 charge and is found within the
atomic nucleus, distinguishing it from the negatively charged electron
and neutral neutron .
10. An atom of carbon-14 has how many neutrons?
Answer: 8
Rationale: Mass number (14) minus atomic number (6) yields 8
neutrons for this carbon isotope .
11. Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁴?
Answer: Sulfur
Rationale: The total of 16 electrons corresponds to atomic number
16, which is sulfur .
12. Which periodic trend increases from left to right across a period?
Answer: Ionization energy
Rationale: Ionization energy increases across a period due to
increasing effective nuclear charge and decreasing atomic radius .
13. Which element has the highest electronegativity?
Answer: Fluorine
Rationale: Fluorine, located in the upper right of the periodic table,
has the highest electronegativity value of all elements .
14. Which type of bond involves the sharing of electrons between
atoms?
Complete Study Guide with Solutions
| 2026 Update:Solved Questions with
Detailed Rationales for General
Chemistry I Exam Success
1. Which property of matter can be observed without changing its
chemical identity?
Answer: Boiling point
Rationale: Physical properties are observable without altering
chemical composition. Flammability, reactivity with acid, and toxicity
involve chemical reactions .
2. How many significant figures are in the measurement 0.003050 m?
Answer: 4
Rationale: Leading zeros are not significant. Digits 3, 0, 5, 0 include
captive zeros and trailing zeros after a decimal, which are significant .
3. Convert 4.58 × 10³ cm³ to m³.
Answer: 4.58 × 10⁻³ m³
Rationale: Using the conversion factor 10⁶ cm³ = 1 m³: (4.58 × 10³) /
10⁶ = 4.58 × 10⁻³ .
,4. A student measures a beaker three times: 25.45 g, 25.46 g, 25.44 g.
The known mass is 25.50 g. The measurements are:
Answer: Precise but not accurate
Rationale: Measurements are close to each other (precise) but differ
from the true value (not accurate) .
5. Dimensional analysis is used to convert units. Which statement is
true?
Answer: Conversion factors are ratios of equivalent quantities
measured in different units
Rationale: Dimensional analysis uses conversion factors as ratios of
equivalent quantities. Units are set up to cancel, leaving the desired
unit .
6. The mass number of an atom is equal to:
Answer: The sum of protons and neutrons
Rationale: Mass number (A) is the total number of protons and
neutrons in the nucleus. Atomic number (Z) is the number of protons .
7. Which of the following is TRUE about isotopes?
Answer: Isotopes have the same number of protons but different
numbers of neutrons
Rationale: Isotopes have the same atomic number (same protons) but
different neutrons. They may be stable or radioactive .
8. The Bohr model of the atom describes electrons in:
Answer: Fixed orbits around the nucleus
Rationale: The Bohr model describes electrons in fixed orbits around
the nucleus .
, 9. Which subatomic particle has a positive charge and is located in the
nucleus?
Answer: Proton
Rationale: The proton carries a +1 charge and is found within the
atomic nucleus, distinguishing it from the negatively charged electron
and neutral neutron .
10. An atom of carbon-14 has how many neutrons?
Answer: 8
Rationale: Mass number (14) minus atomic number (6) yields 8
neutrons for this carbon isotope .
11. Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁴?
Answer: Sulfur
Rationale: The total of 16 electrons corresponds to atomic number
16, which is sulfur .
12. Which periodic trend increases from left to right across a period?
Answer: Ionization energy
Rationale: Ionization energy increases across a period due to
increasing effective nuclear charge and decreasing atomic radius .
13. Which element has the highest electronegativity?
Answer: Fluorine
Rationale: Fluorine, located in the upper right of the periodic table,
has the highest electronegativity value of all elements .
14. Which type of bond involves the sharing of electrons between
atoms?
