CHEM 101 Final Assessment Review Latest
Update Rated A+
1. Which of the following elements has the highest electronegativity?
A. Sodium
B. Chlorine
C. Oxygen
D. Potassium
Rationale: Electronegativity increases across a period and decreases down a group.
Oxygen is higher than chlorine in electronegativity.
2. What is the molarity of a solution prepared by dissolving 10.0 g of NaOH in 250 mL of
solution?
A. 0.40 M
B. 1.0 M
C. 0.25 M
D. 0.10 M
Rationale: Moles NaOH = 10.0 g ÷ 40.0 g/mol = 0.25 mol.
Molarity = 0.25 mol ÷ 0.250 L = 1.0 M.
Correction: Wait — calculation shows 1.0 M. Correct answer is B. 1.0 M.
3. Which statement about ionic compounds is true?
A. They conduct electricity in solid state.
B. They have low melting points.
C. They are soluble in water.
D. They consist of molecules held by covalent bonds.
Rationale: Ionic compounds dissociate into ions in aqueous solution, allowing
conductivity. They do not conduct in solid state.
4. A reaction has ΔH = -250 kJ. Which statement is correct?
A. The reaction is endothermic.
B. The reaction releases heat.
C. The reaction absorbs heat.
D. The reaction requires energy input.
Rationale: Negative enthalpy change indicates exothermic reaction.
5. What is the pH of a 0.001 M HCl solution?
A. 1
B. 2
C. 3
D. 11
Rationale: Strong acid, [H⁺] = 0.001 M = 1 × 10⁻³. pH = -log(10⁻³) = 3.
6. Which orbital has the highest energy in the ground-state electron configuration of
,oxygen?
A. 2s
B. 2p
C. 1s
D. 3s
Rationale: Oxygen’s ground state ends in 2p⁴; 2p orbitals are higher in energy than 2s
and 1s.
7. Which of the following is a chemical change?
A. Ice melting
B. Water boiling
C. Iron rusting
D. Sugar dissolving
Rationale: Rusting produces a new substance (iron oxide), unlike physical changes.
8. How many moles of CO₂ are produced when 2 moles of C₂H₆ combust completely?
A. 2
B. 4
C. 6
D. 8
Rationale: Balanced equation: 2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O. Two moles of ethane
yield 4 moles CO₂. Correction: Answer is B. 4.
9. Which solution has the highest boiling point?
A. 1 M NaCl
B. 1 M glucose
C. 0.5 M NaCl
D. Pure water
Rationale: NaCl dissociates into 2 particles (van’t Hoff factor i=2), raising boiling point
more than non-electrolyte glucose.
10. Which gas law relates pressure and volume at constant temperature?
A. Boyle’s Law
B. Charles’s Law
C. Gay-Lussac’s Law
D. Avogadro’s Law
Rationale: P ∝ 1/V at constant T.
11. Which of the following is a strong acid?
A. HF
B. H₂CO₃
C. HCl
D. CH₃COOH
Rationale: HCl dissociates completely in water.
12. What is the oxidation state of sulfur in SO₄²⁻?
, A. +2
B. +4
C. +6
D. -2
Rationale: Oxygen is -2 × 4 = -8. Total charge = -2. So sulfur must be +6.
13. Which of the following compounds is polar?
A. CO₂
B. CH₄
C. NH₃
D. CCl₄
Rationale: Trigonal pyramidal geometry creates net dipole.
14. Which type of radiation has the highest penetrating power?
A. Alpha
B. Beta
C. Gamma
D. Neutron
Rationale: Gamma rays penetrate deeply compared to alpha and beta.
15. What is the molar mass of Ca(OH)₂?
A. 54 g/mol
B. 74 g/mol
C. 90 g/mol
D. 58 g/mol
Rationale: Ca=40, O=16×2=32, H=1×2=2 → total = 74 g/mol.
16. Which of the following is an endothermic process?
A. Freezing water
B. Condensing steam
C. Melting ice
D. Combustion of methane
Rationale: Heat is absorbed to break intermolecular forces.
17. Which of the following has the smallest atomic radius?
A. Na
B. Mg
C. Al
D. Si
Rationale: Atomic radius decreases across a period; Si is farthest right.
18. Which of the following is a weak base?
A. NaOH
B. KOH
C. NH₃
D. Ca(OH)₂
Update Rated A+
1. Which of the following elements has the highest electronegativity?
A. Sodium
B. Chlorine
C. Oxygen
D. Potassium
Rationale: Electronegativity increases across a period and decreases down a group.
Oxygen is higher than chlorine in electronegativity.
2. What is the molarity of a solution prepared by dissolving 10.0 g of NaOH in 250 mL of
solution?
A. 0.40 M
B. 1.0 M
C. 0.25 M
D. 0.10 M
Rationale: Moles NaOH = 10.0 g ÷ 40.0 g/mol = 0.25 mol.
Molarity = 0.25 mol ÷ 0.250 L = 1.0 M.
Correction: Wait — calculation shows 1.0 M. Correct answer is B. 1.0 M.
3. Which statement about ionic compounds is true?
A. They conduct electricity in solid state.
B. They have low melting points.
C. They are soluble in water.
D. They consist of molecules held by covalent bonds.
Rationale: Ionic compounds dissociate into ions in aqueous solution, allowing
conductivity. They do not conduct in solid state.
4. A reaction has ΔH = -250 kJ. Which statement is correct?
A. The reaction is endothermic.
B. The reaction releases heat.
C. The reaction absorbs heat.
D. The reaction requires energy input.
Rationale: Negative enthalpy change indicates exothermic reaction.
5. What is the pH of a 0.001 M HCl solution?
A. 1
B. 2
C. 3
D. 11
Rationale: Strong acid, [H⁺] = 0.001 M = 1 × 10⁻³. pH = -log(10⁻³) = 3.
6. Which orbital has the highest energy in the ground-state electron configuration of
,oxygen?
A. 2s
B. 2p
C. 1s
D. 3s
Rationale: Oxygen’s ground state ends in 2p⁴; 2p orbitals are higher in energy than 2s
and 1s.
7. Which of the following is a chemical change?
A. Ice melting
B. Water boiling
C. Iron rusting
D. Sugar dissolving
Rationale: Rusting produces a new substance (iron oxide), unlike physical changes.
8. How many moles of CO₂ are produced when 2 moles of C₂H₆ combust completely?
A. 2
B. 4
C. 6
D. 8
Rationale: Balanced equation: 2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O. Two moles of ethane
yield 4 moles CO₂. Correction: Answer is B. 4.
9. Which solution has the highest boiling point?
A. 1 M NaCl
B. 1 M glucose
C. 0.5 M NaCl
D. Pure water
Rationale: NaCl dissociates into 2 particles (van’t Hoff factor i=2), raising boiling point
more than non-electrolyte glucose.
10. Which gas law relates pressure and volume at constant temperature?
A. Boyle’s Law
B. Charles’s Law
C. Gay-Lussac’s Law
D. Avogadro’s Law
Rationale: P ∝ 1/V at constant T.
11. Which of the following is a strong acid?
A. HF
B. H₂CO₃
C. HCl
D. CH₃COOH
Rationale: HCl dissociates completely in water.
12. What is the oxidation state of sulfur in SO₄²⁻?
, A. +2
B. +4
C. +6
D. -2
Rationale: Oxygen is -2 × 4 = -8. Total charge = -2. So sulfur must be +6.
13. Which of the following compounds is polar?
A. CO₂
B. CH₄
C. NH₃
D. CCl₄
Rationale: Trigonal pyramidal geometry creates net dipole.
14. Which type of radiation has the highest penetrating power?
A. Alpha
B. Beta
C. Gamma
D. Neutron
Rationale: Gamma rays penetrate deeply compared to alpha and beta.
15. What is the molar mass of Ca(OH)₂?
A. 54 g/mol
B. 74 g/mol
C. 90 g/mol
D. 58 g/mol
Rationale: Ca=40, O=16×2=32, H=1×2=2 → total = 74 g/mol.
16. Which of the following is an endothermic process?
A. Freezing water
B. Condensing steam
C. Melting ice
D. Combustion of methane
Rationale: Heat is absorbed to break intermolecular forces.
17. Which of the following has the smallest atomic radius?
A. Na
B. Mg
C. Al
D. Si
Rationale: Atomic radius decreases across a period; Si is farthest right.
18. Which of the following is a weak base?
A. NaOH
B. KOH
C. NH₃
D. Ca(OH)₂
