CHEM 101 Final Assessment Latest Update Graded A+
Section A: Atomic Structure & Periodicity
1. Which of the following has the largest atomic radius?
A. Na
B. Mg
C. Al
• D) K
Rationale: Atomic radius increases down a group; potassium is lower in Group 1 than
sodium.
2. The number of protons in an isotope of carbon-14 is:
A. 6
B. 7
C. 8
D. 14
Rationale: Carbon always has 6 protons; the isotope number refers to protons +
neutrons.
Section B: Stoichiometry
3. How many moles of O₂ are required to completely combust 2 moles of CH₄?
A. 2
• B) 4
C. 1
D. 8
Rationale: CH₄ + 2O₂ → CO₂ + 2H₂O. Two moles CH₄ need 4 moles O₂.
4. A solution contains 0.5 mol NaCl in 1 L. What is its molarity?
A. 0.25 M
• B) 0.50 M
C. 1.00 M
D. 2.00 M
Rationale: Molarity = moles solute / liters solution = 0.5/1 = 0.5 M.
Section C: Chemical Bonding
5. Which molecule has a trigonal planar geometry?
A. NH₃
• B) BF₃
C. H₂O
D. CH₄
Rationale: BF₃ has three bonding pairs, no lone pairs → trigonal planar.
6. Which bond is most polar?
, A. C–H
B. N–O
• C) H–F
D. O–O
Rationale: Fluorine is the most electronegative element, making H–F highly polar.
Section D: Thermochemistry
7. If ΔH = –250 kJ for a reaction, the process is:
A. Endothermic
• B) Exothermic
C. Neutral
D. Non-spontaneous
Rationale: Negative enthalpy change indicates heat release (exothermic).
8. Calculate q when 50 g water absorbs 4.18 J/g·°C and temperature rises 10°C.
A. 209 J
B. 418 J
• C) 2090 J
D. 4180 J
Rationale: q = m·c·ΔT = 50 × 4.18 × 10 = 2090 J.
Section E: Solutions & Equilibria
9. A solution with [H⁺] = 1 × 10⁻³ M has a pH of:
A. 2
• B) 3
C. 4
D. 5
Rationale: pH = –log[H⁺] = –log(10⁻³) = 3.
10. Increasing temperature generally shifts equilibrium of an endothermic reaction:
A. Left
• B) Right
C. No change
D. Depends on catalyst
Rationale: Heat acts as a reactant in endothermic reactions; adding heat drives
equilibrium forward.
Section F: Gas Laws
11. At constant temperature, Boyle’s Law states:
A. V∝T
• B) V ∝ 1/P
C. P∝T
Section A: Atomic Structure & Periodicity
1. Which of the following has the largest atomic radius?
A. Na
B. Mg
C. Al
• D) K
Rationale: Atomic radius increases down a group; potassium is lower in Group 1 than
sodium.
2. The number of protons in an isotope of carbon-14 is:
A. 6
B. 7
C. 8
D. 14
Rationale: Carbon always has 6 protons; the isotope number refers to protons +
neutrons.
Section B: Stoichiometry
3. How many moles of O₂ are required to completely combust 2 moles of CH₄?
A. 2
• B) 4
C. 1
D. 8
Rationale: CH₄ + 2O₂ → CO₂ + 2H₂O. Two moles CH₄ need 4 moles O₂.
4. A solution contains 0.5 mol NaCl in 1 L. What is its molarity?
A. 0.25 M
• B) 0.50 M
C. 1.00 M
D. 2.00 M
Rationale: Molarity = moles solute / liters solution = 0.5/1 = 0.5 M.
Section C: Chemical Bonding
5. Which molecule has a trigonal planar geometry?
A. NH₃
• B) BF₃
C. H₂O
D. CH₄
Rationale: BF₃ has three bonding pairs, no lone pairs → trigonal planar.
6. Which bond is most polar?
, A. C–H
B. N–O
• C) H–F
D. O–O
Rationale: Fluorine is the most electronegative element, making H–F highly polar.
Section D: Thermochemistry
7. If ΔH = –250 kJ for a reaction, the process is:
A. Endothermic
• B) Exothermic
C. Neutral
D. Non-spontaneous
Rationale: Negative enthalpy change indicates heat release (exothermic).
8. Calculate q when 50 g water absorbs 4.18 J/g·°C and temperature rises 10°C.
A. 209 J
B. 418 J
• C) 2090 J
D. 4180 J
Rationale: q = m·c·ΔT = 50 × 4.18 × 10 = 2090 J.
Section E: Solutions & Equilibria
9. A solution with [H⁺] = 1 × 10⁻³ M has a pH of:
A. 2
• B) 3
C. 4
D. 5
Rationale: pH = –log[H⁺] = –log(10⁻³) = 3.
10. Increasing temperature generally shifts equilibrium of an endothermic reaction:
A. Left
• B) Right
C. No change
D. Depends on catalyst
Rationale: Heat acts as a reactant in endothermic reactions; adding heat drives
equilibrium forward.
Section F: Gas Laws
11. At constant temperature, Boyle’s Law states:
A. V∝T
• B) V ∝ 1/P
C. P∝T
