IB Chemistry SL / HL
Exam Questions And
Correct Answers
(Verified Answers) Plus
Rationales 2025/2026
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1. Which particle has a relative charge of -1 and negligible
mass?
A. Proton
B. Neutron
C. Electron
D. Positron
Answer: C
,Rationale: Electrons carry -1 charge and have very small
mass compared to nucleons.
2. The number of protons in an atom is called its:
A. Mass number
B. Atomic number
C. Isotopic number
D. Relative atomic mass
Answer: B
Rationale: Atomic number defines the number of protons.
3. Which subatomic particle determines the identity of an
element?
A. Neutron
B. Electron
C. Proton
D. Isotope
Answer: C
Rationale: Element identity depends on proton number.
4. Which is an example of a physical change?
A. Burning magnesium
B. Rusting iron
C. Melting ice
D. Digestion
,Answer: C
Rationale: Melting is a phase change only.
5. The empirical formula of C₆H₁₂O₆ is:
A. CHO
B. C₂H₄O₂
C. C₆H₁₂O₆
D. CH₂O
Answer: D
Rationale: Simplest ratio is CH₂O.
6. Avogadro’s constant is approximately:
A. 6.02 × 10²³ mol⁻¹
B. 3.00 × 10⁸ m/s
C. 1.60 × 10⁻¹⁹ C
D. 9.81 m/s²
Answer: A
Rationale: Number of particles per mole.
7. A covalent bond is formed by:
A. Electron transfer
B. Proton sharing
C. Electron sharing
D. Neutron transfer
Answer: C
Rationale: Covalent bonds involve shared electron pairs.
, 8. Which is a strong electrolyte?
A. Ethanol
B. Sugar solution
C. Sodium chloride solution
D. Pure water
Answer: C
Rationale: NaCl fully dissociates in water.
9. Which type of bond is in NaCl?
A. Covalent
B. Metallic
C. Ionic
D. Hydrogen
Answer: C
Rationale: Metal + non-metal forms ionic bond.
10. The relative atomic mass is based on:
A. Protons only
B. Neutrons only
C. Weighted isotopic abundance
D. Electron mass
Answer: C
Rationale: Includes isotope proportions.
11. Which gas deviates most from ideal behavior?
Exam Questions And
Correct Answers
(Verified Answers) Plus
Rationales 2025/2026
Q&A | Instant
Download Pdf
1. Which particle has a relative charge of -1 and negligible
mass?
A. Proton
B. Neutron
C. Electron
D. Positron
Answer: C
,Rationale: Electrons carry -1 charge and have very small
mass compared to nucleons.
2. The number of protons in an atom is called its:
A. Mass number
B. Atomic number
C. Isotopic number
D. Relative atomic mass
Answer: B
Rationale: Atomic number defines the number of protons.
3. Which subatomic particle determines the identity of an
element?
A. Neutron
B. Electron
C. Proton
D. Isotope
Answer: C
Rationale: Element identity depends on proton number.
4. Which is an example of a physical change?
A. Burning magnesium
B. Rusting iron
C. Melting ice
D. Digestion
,Answer: C
Rationale: Melting is a phase change only.
5. The empirical formula of C₆H₁₂O₆ is:
A. CHO
B. C₂H₄O₂
C. C₆H₁₂O₆
D. CH₂O
Answer: D
Rationale: Simplest ratio is CH₂O.
6. Avogadro’s constant is approximately:
A. 6.02 × 10²³ mol⁻¹
B. 3.00 × 10⁸ m/s
C. 1.60 × 10⁻¹⁹ C
D. 9.81 m/s²
Answer: A
Rationale: Number of particles per mole.
7. A covalent bond is formed by:
A. Electron transfer
B. Proton sharing
C. Electron sharing
D. Neutron transfer
Answer: C
Rationale: Covalent bonds involve shared electron pairs.
, 8. Which is a strong electrolyte?
A. Ethanol
B. Sugar solution
C. Sodium chloride solution
D. Pure water
Answer: C
Rationale: NaCl fully dissociates in water.
9. Which type of bond is in NaCl?
A. Covalent
B. Metallic
C. Ionic
D. Hydrogen
Answer: C
Rationale: Metal + non-metal forms ionic bond.
10. The relative atomic mass is based on:
A. Protons only
B. Neutrons only
C. Weighted isotopic abundance
D. Electron mass
Answer: C
Rationale: Includes isotope proportions.
11. Which gas deviates most from ideal behavior?
