IJMB Chemistry
Past Questions
19+ verified Chemistry past questions for IJMB. Step-by-step worked answers in 5 Nigerian languages.
Chemistry topics (2)
Sample Chemistry past questions
1. Avogadro's number ≈
- A. 6.02 × 10²³
- B. 9.8 × 10²³
- C. 1.6 × 10⁻¹⁹
- D. 3 × 10⁸
Answer: A
2. Carbon's electron configuration.
- A. 2,2
- B. 2,4
- C. 2,6
- D. 2,8
Answer: B
3. The atomic number equals the number of:
- A. Neutrons
- B. Protons
- C. Electrons + neutrons
- D. Molecules
Answer: B
4. An acid turns blue litmus:
- A. Green
- B. Red
- C. Yellow
- D. Blue
Answer: B
5. Diamond and graphite are forms of:
- A. Silicon
- B. Carbon
- C. Sulphur
- D. Iron
Answer: B
6. The pH of a strong acid is:
- A. 7
- B. Below 7
- C. Above 7
- D. Exactly 14
Answer: B
7. Electrolysis requires:
- A. Heat only
- B. Electric current
- C. Light
- D. Pressure
Answer: B
8. Atomic number = number of:
- A. neutrons
- B. protons
- C. electrons in outer shell
- D. molecules
Answer: B
AI Explanation
Atomic number Z = number of protons (identifies the element).
9. Which is a noble gas?
- A. chlorine
- B. hydrogen
- C. neon
- D. nitrogen
Answer: C
AI Explanation
Noble gases (Group 18): He, Ne, Ar, Kr, Xe, Rn.
10. pH of pure water at 25°C:
- A. 5
- B. 6
- C. 7
- D. 8
Answer: C
AI Explanation
Pure water is neutral with pH 7 at 25°C.
11. Avogadro's number is approximately:
- A. 6.022 × 10²³
- B. 6.022 × 10²²
- C. 9.81 × 10²³
- D. 3 × 10⁸
Answer: A
AI Explanation
Avogadro = 6.022 × 10²³ particles per mole.
12. Formula of methane:
- A. CH₂
- B. CH₃
- C. CH₄
- D. C₂H₄
Answer: C
AI Explanation
Methane = CH₄ (one carbon, four hydrogens).
13. Oxidation is:
- A. gain of electrons
- B. loss of electrons
- C. loss of protons
- D. gain of neutrons
Answer: B
AI Explanation
Oxidation Is Loss (of electrons). Reduction Is Gain (OIL RIG).
14. Reduction is:
- A. loss of electrons
- B. gain of electrons
- C. loss of mass
- D. gain of energy only
Answer: B
AI Explanation
Reduction is the gain of electrons (RIG — Reduction Is Gain).
15. Which element forms organic compounds?
- A. nitrogen
- B. carbon
- C. sulphur
- D. phosphorus
Answer: B
AI Explanation
Carbon's tetravalency and catenation make it the backbone of organic chemistry.
16. Acid + base produces:
- A. only acid
- B. only base
- C. salt and water
- D. gas only
Answer: C
AI Explanation
Neutralisation: acid + base → salt + water.
17. Alkali metals are found in Group:
- A. 1
- B. 2
- C. 17
- D. 18
Answer: A
AI Explanation
Group 1 (alkali metals): Li, Na, K, Rb, Cs, Fr.
18. Halogens are found in Group:
- A. 1
- B. 2
- C. 17
- D. 18
Answer: C
AI Explanation
Group 17 (halogens): F, Cl, Br, I, At.
19. Empirical formula of glucose (C₆H₁₂O₆):
- A. CHO
- B. CH₂O
- C. CH₂O₃
- D. C₂H₂O
Answer: B
AI Explanation
C₆H₁₂O₆ simplifies to CH₂O (1:2:1 ratio).
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