Qualitative Chemistry Comprehension Questions Bank
Welcome to qChem+! Chapter 2 of HSC Chemistry 1st Paper — Qualitative Chemistry — carries a significant weight in both HSC Board Examinations and University Admission Tests (Engineering, Medical, and Public Universities).
In Creative Questions (CQ), Comprehension Questions (Question ‘b’ / 2-marks) require a clear understanding of core scientific laws, electron configuration rules, quantum mechanics, analytical reactions, and mathematical reasoning. Writing logical, precise, and well-structured answers with correct chemical formulas is essential for securing full marks.
To help NCTB HSC English Version students achieve top grades, we have compiled all 53 authentic comprehension questions from past Board Exams (2015–2026) organized by topic for focused revision and self-assessment.
Check out the post below to get all these board exam questions along with their correct answers:
📌 1. Quantum Numbers, Sub-shells & Electron Capacity
1. Why is a 2d-orbital not possible?
[Md(I) B 26; MB, CB 22; MB, RB 21; JB 19; CB 17; BB 16; CB 15]
2. Why is a 3f-orbital not possible?
[CtgB 22; DB, BB 21; CtgB 19]
3. Fe²⁺ and Co³⁺ are isoelectronic with each other — Explain.
[DinB 19]
4. The f-subshell contains 7 orbitals — Explain.
[MB, CB 25]
📌 2. Aufbau Principle, Pauli’s Exclusion Principle & Hund’s Rule
5. Explain the Aufbau Principle.
[JB 21; CB 19]
6. Between 3d and 4p orbitals, in which one does an electron enter first?
[DB 16]
7. Between 4d and 4f, in which orbital does an electron enter first and why?
[CB 21]
8. Why does the 19th electron of K enter the 4s orbital instead of the 3d orbital?
[DB, RB, DinB, SB, JB 18; RB 15]
9. Why does the 37th electron of Rb enter the 5s orbital instead of the 4d orbital?
[DinB 21]
10. Explain Pauli’s Exclusion Principle.
[DinB 22; DB, RB, DinB, SB, JB 18]
11. Why is a half-filled ‘p’ orbital more stable?
[CtgB 21]
12. “A p-subshell can hold a maximum of 6 electrons” — Explain according to Pauli’s Exclusion Principle.
[SB 19]
13. Explain how the electronic configuration of He obeys Pauli’s Exclusion Principle.
14. Why does the 19th electron of a calcium atom enter the 4s orbital instead of the 3d orbital? Explain.
[Md(I) B 26; CtgB 21]
15. Explain Hund’s Rule along with electron configuration.
[RB 22]
16. Why is Hund’s rule of maximum multiplicity applicable to the electron configuration of N?
[All(I) B. 26]
17. Explain the electronic configuration of phosphorus according to Hund’s Rule.
[DB 19]
18. Between Fe²⁺ and Fe³⁺ ions, which one is more stable? Explain.
[Md(I) B 26; DB 21]
19. Why does the normal electronic configuration of Cu show an exception?
[CB 19; RB, CB, CtgB, BB 18]
20. Why is the electronic configuration of Cr (24) an exception to the general rule?
[CB 25; JB 23; MB 22; MB, CB 21; CtgB, SB 15]
📌 3. Electromagnetic Spectrum
21. Calculate the energy of a radiation having a wavelength of 675 nm.
[BB 17]
📌 4. Bohr Atom Model & Hydrogen Spectrum
22. Bohr’s theory is applicable for He⁺ — Explain.
[CtgB 17]
23. Why are many spectral lines observed in the atomic spectrum of hydrogen despite having only one electron?
[RB 16]
24. How is the hydrogen spectrum produced? Explain.
[DB 25; BB 23]
📌 5. Applications of UV & IR Rays
25. Why are UV rays used in detecting fake passports or currency notes?
[All B. 26; CB 19; BB 17; DB 16 / DinB, CtgB, JB 25; DinB, SB 23; JB 22]
26. How is fluorescence / phosphorescence created? Explain.
[DB 15 / JB 17]
27. Write down the uses of IR rays in medical science.
[DinB 23; SB 22; SB 19]
28. How are IR rays related to global warming?
📌 6. Qualitative Chemical Analysis (Wet & Flame Tests)
29. How will you detect the presence of Na⁺ ion in a solution?
[RB, SB 21]
30. How will you detect Al³⁺ ion in a solution?
[DinB 17; CB 16]
31. Why is concentrated HCl acid used in flame tests?
[All B. 26; DB, BB 19; DB, CB, SB 17; CtgB 16; DB, CtgB 15]
32. How can NH₄⁺ ion be detected in a solution?
[BB 16]
33. How will you detect Fe³⁺ ion in a solution?
[JB 16]
34. How will you detect SO₄²⁻ ion in a solution? Write down the reaction.
[All(I) B. 26; DB 25; BB 21; SB 17]
📌 7. Solubility, Solubility Product & Common Ion Effect
35. What is meant by “Solubility of a salt is 30”?
[JB 21]
36. The solubility of NaCl at 25°C is 36 — Explain.
[MB 21; DB 19]
37. What is meant by the solubility product of CaCO₃ being 8.7 × 10⁻⁹?
[RB 21; DinB 16]
38. What do you understand by solubility product?
[All(I) B. 26; DB 21; DinB 17]
39. What is meant by the solubility product of Zn(OH)₂ at 25°C being 1 × 10⁻¹⁷?
[SB 19]
40. The solubility product of Al(OH)₃ is 3.7 × 10⁻¹⁵ — Explain the meaning of this statement.
[JB 21]
41. What is meant by the solubility product of BaSO₄ at room temperature being 1.1 × 10⁻¹⁰?
[RB 17]
42. What is meant by the solubility product of M(OH)₃ at 25°C being 2.5 × 10⁻³⁹?
[SB 16]
43. Explain the effect of temperature on solubility.
[JB 22; RB 17]
44. Why does the solubility product increase with an increase in temperature?
[MB 21]
45. Why does the ionic product of water change with temperature?
[DB 22; DB 19]
46. Why does solubility decrease due to the common ion effect?
[RB 22; RB 19; SB 17]
47. “The solubility of hydrated salts increases up to a certain temperature and then decreases with further temperature rise” — Explain.
[RB 19]
48. What is meant by the solubility of KNO₃ at 25°C being 31.6?
[CB 17]
49. Why does the solubility of metal chlorides decrease in an HCl solution? Explain.
[MdB 26]
📌 8. Crystallization, Distillation & Chromatography
50. Why is HCl used in the crystallization of pure NaCl?
[DinB 25; DB 16]
51. Why is HCl used for purifying impure NaCl in solution? Explain.
[MdB 18]
52. Why is ether not rendered completely anhydrous during distillation?
[JB 17]
53. Write down the working principle of chromatography.
[DinB 16]
54. Why is the value of R𝒇 less than 1?
[BB 19; CB, CtgB, BB 18; RB 17; SB 15]
55. Why does R𝒇 have no unit?
[JB 19]
56. Why is the value of R𝒇 affected by the solvent in paper chromatography?
[All(I) B. 26]
Abbreviations used: All.B = All Board, DB = Dhaka, RB = Rajshahi, CB = Comilla, JB = Jessore, CtgB = Chittagong, BB = Barisal, SB = Sylhet, DinB = Dinajpur, MB = Mymensingh, MdB = Madrasah, Md(I)B = Madrasah (Irregular).
💡 Top Exam Preparation Tips from qChem+:
- Write concise, point-to-point scientific arguments (2–3 sentences per answer) for full 2 marks in CQs.
- Pay close attention to chemical formulas, charges (e.g., Fe³⁺, Al³⁺, SO₄²⁻), and units in physical chemistry definitions.
- Bookmark & Share: Keep qChem+ bookmarked for more HSC Chemistry English Version board question banks and study materials!
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