CHEM 101 Winter 2026 Exam 2 Version C |
Complete Questions and Correct Answers |
Verified Answer Key.
CHEM 101 Winter 2026 Exam 2 Version C
COMPLETE PRACTICE EXAM: 70 QUESTIONS WITH VERIFIED ANSWERS
PART I:
1. Please choose the letter "C" as your answer for this question.
A) A
B) B
C) C
D) D
E) E
Rationale: This is a standard instruction question included to ensure you are
reading the directions carefully and filling in your answer sheet correctly. The
answer is C .
2. Of the choices below, which one is NOT an ionic compound?
A) MgCl₂
B) NaCl
C) FeCl₂
D) PCl₅
E) RbCl
,Rationale: PCl₅ (phosphorus pentachloride) is a covalent compound formed
between two nonmetals (P and Cl). The other options contain a metal and
nonmetal, forming ionic compounds .
3. In which set of elements would all members be expected to have very similar
chemical properties?
A) S, Se, Si
B) O, S, Se
C) Na, Mg, K
D) N, O, F
E) Ne, Na, Mg
Rationale: Elements in the same group (vertical column) of the periodic table have
similar chemical properties because they have the same number of valence
electrons. O, S, and Se are all in Group 6A and have six valence electrons .
4. Calculate the percentage by mass of lead in Pb(NO₃)₂.
A) 62.6%
B) 38.6%
C) 71.2%
D) 65.3%
E) 44.5%
Rationale: Molar mass of Pb(NO₃)₂ = 207.2 + 2(14.01 + 3×16.00) = 207.2 + 2(62.01)
= 331.22 g/mol. %Pb = (207.2/331.22) × 100 = 62.6% .
5. How many orbitals are contained in the third principal level (n = 3) of a given
atom?
A) 3
B) 18
, C) 9
D) 7
E) 5
Rationale: The number of orbitals in a principal level is n². For n=3, there are 3² = 9
orbitals (one 3s, three 3p, and five 3d orbitals) .
6. For a hydrogen atom, calculate the wavelength of an emitted photon in the
Lyman series that results from the transition n = 3 to n = 1.
A) 95.0 nm
B) 91.2 nm
C) 102.6 nm
D) 434.1 nm
E) 1005 nm
Rationale: ΔE = -RH(1/nf² - 1/ni²) = -2.179×10⁻¹⁸(1/1² - 1/3²) = -2.179×10⁻¹⁸(1 - 1/9)
= -1.937×10⁻¹⁸ J. E = hc/λ, so λ = hc/E = (6.63×10⁻³⁴)(3.00×10⁸)/(1.937×10⁻¹⁸) =
1.026×10⁻⁷ m = 102.6 nm .
7. Which of the following elements is NOT a metal?
A) Ba
B) Mg
C) Pb
D) Ga
E) Xe
Rationale: Xenon (Xe) is a noble gas, not a metal. Ba (barium), Mg (magnesium),
Pb (lead), and Ga (gallium) are all metals .
8. The element that corresponds to the electron configuration
1s²2s²2p⁶3s²3p⁶4s¹3d⁵ is:
Complete Questions and Correct Answers |
Verified Answer Key.
CHEM 101 Winter 2026 Exam 2 Version C
COMPLETE PRACTICE EXAM: 70 QUESTIONS WITH VERIFIED ANSWERS
PART I:
1. Please choose the letter "C" as your answer for this question.
A) A
B) B
C) C
D) D
E) E
Rationale: This is a standard instruction question included to ensure you are
reading the directions carefully and filling in your answer sheet correctly. The
answer is C .
2. Of the choices below, which one is NOT an ionic compound?
A) MgCl₂
B) NaCl
C) FeCl₂
D) PCl₅
E) RbCl
,Rationale: PCl₅ (phosphorus pentachloride) is a covalent compound formed
between two nonmetals (P and Cl). The other options contain a metal and
nonmetal, forming ionic compounds .
3. In which set of elements would all members be expected to have very similar
chemical properties?
A) S, Se, Si
B) O, S, Se
C) Na, Mg, K
D) N, O, F
E) Ne, Na, Mg
Rationale: Elements in the same group (vertical column) of the periodic table have
similar chemical properties because they have the same number of valence
electrons. O, S, and Se are all in Group 6A and have six valence electrons .
4. Calculate the percentage by mass of lead in Pb(NO₃)₂.
A) 62.6%
B) 38.6%
C) 71.2%
D) 65.3%
E) 44.5%
Rationale: Molar mass of Pb(NO₃)₂ = 207.2 + 2(14.01 + 3×16.00) = 207.2 + 2(62.01)
= 331.22 g/mol. %Pb = (207.2/331.22) × 100 = 62.6% .
5. How many orbitals are contained in the third principal level (n = 3) of a given
atom?
A) 3
B) 18
, C) 9
D) 7
E) 5
Rationale: The number of orbitals in a principal level is n². For n=3, there are 3² = 9
orbitals (one 3s, three 3p, and five 3d orbitals) .
6. For a hydrogen atom, calculate the wavelength of an emitted photon in the
Lyman series that results from the transition n = 3 to n = 1.
A) 95.0 nm
B) 91.2 nm
C) 102.6 nm
D) 434.1 nm
E) 1005 nm
Rationale: ΔE = -RH(1/nf² - 1/ni²) = -2.179×10⁻¹⁸(1/1² - 1/3²) = -2.179×10⁻¹⁸(1 - 1/9)
= -1.937×10⁻¹⁸ J. E = hc/λ, so λ = hc/E = (6.63×10⁻³⁴)(3.00×10⁸)/(1.937×10⁻¹⁸) =
1.026×10⁻⁷ m = 102.6 nm .
7. Which of the following elements is NOT a metal?
A) Ba
B) Mg
C) Pb
D) Ga
E) Xe
Rationale: Xenon (Xe) is a noble gas, not a metal. Ba (barium), Mg (magnesium),
Pb (lead), and Ga (gallium) are all metals .
8. The element that corresponds to the electron configuration
1s²2s²2p⁶3s²3p⁶4s¹3d⁵ is:
