SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs (2026–27) – Assam Eduverse
Build a strong foundation in atomic structure with these SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs (2026–27), carefully aligned with the latest ASSEB syllabus and current exam pattern. These SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs feature a mix of conceptual and numerical questions that help students understand core topics while preparing effectively for board exams.
Curated by Assam Eduverse subject experts, these SEBA Class 9 Science Chapter 4 MCQs cover essential concepts such as subatomic particles, atomic models (Thomson, Rutherford, and Bohr), atomic and mass numbers, isotopes, and isobars. Solving these Structure of the Atom MCQs Class 9 SEBA and Assam Board Class 9 Science objective questions enhances accuracy and conceptual understanding. You can also practice more from Class 9 Science chapterwise MCQs and SEBA Class 9 MCQs.
Consistent revision of these ASSEB Class 9 Science Important MCQs will help you gain confidence and improve performance in exams. For detailed explanations, visit SEBA Class 9 Science Chapter 4 Structure of the Atom Solutions, or explore additional resources like SEBA Class 9 & 10 study materials and SEBA Class 9 syllabus.
SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs – ASSEB 2026–27 Board Exam Practice
Table of Contents
Q1. Canal rays are positively charged radiations discovered by:
(a) J.J. Thomson
(b) E. Goldstein
(c) Rutherford
(d) Chadwick
Answer: (b) E. Goldstein
Q2. The charge on a proton is:
(a) –1
(b) +1
(c) 0
(d) +2
Answer: (b) +1
Q3. The mass of a proton is approximately:
(a) Equal to electron
(b) Negligible
(c) One unit
(d) Half unit
Answer: (c) One unit
Q4. Thomson proposed that electrons are embedded in a:
(a) Negatively charged sphere
(b) Neutral sphere
(c) Positively charged sphere
(d) Hollow space
Answer: (c) Positively charged sphere
Q5. According to Thomson’s model, an atom is electrically neutral because:
(a) It has no charge
(b) Positive and negative charges are equal
(c) It contains neutrons
(d) Electrons have no mass
Answer: (b) Positive and negative charges are equal
Q6. Rutherford used which metal foil in his experiment?
(a) Silver
(b) Platinum
(c) Gold
(d) Copper
Answer: (c) Gold
Q7. Most alpha particles passed through the gold foil because:
(a) The foil was thick
(b) Atom is mostly empty space
(c) Alpha particles are light
(d) Nucleus is large
Answer: (b) Atom is mostly empty space
Q8. The positively charged center of an atom is called:
(a) Electron
(b) Proton
(c) Nucleus
(d) Shell
Answer: (c) Nucleus
Q9. The size of nucleus compared to atom is:
(a) Larger
(b) Equal
(c) Very small
(d) Half
Answer: (c) Very small
Q10. Who discovered neutron?
(a) Rutherford
(b) J.J. Thomson
(c) Chadwick
(d) Goldstein
Answer: (c) Chadwick
Q11. The maximum number of electrons in K-shell is:
(a) 8
(b) 2
(c) 18
(d) 32
Answer: (b) 2
Q12. The maximum number of electrons in L-shell is:
(a) 2
(b) 4
(c) 8
(d) 18
Answer: (c) 8
Q13. The formula to calculate maximum number of electrons in a shell is:
(a) n²
(b) 2n
(c) 2n²
(d) n³
Answer: (c) 2n²
Q14. The outermost shell of an atom can have maximum:
(a) 2 electrons
(b) 4 electrons
(c) 6 electrons
(d) 8 electrons
Answer: (d) 8 electrons
Q15. Valency of an atom depends on:
(a) Total electrons
(b) Neutrons
(c) Electrons in outermost shell
(d) Atomic mass
Answer: (c) Electrons in outermost shell
Q16. Atomic number is equal to number of:
(a) Neutrons
(b) Electrons
(c) Protons
(d) Nucleons
Answer: (c) Protons
Q17. Mass number is equal to:
(a) Protons + electrons
(b) Protons + neutrons
(c) Neutrons only
(d) Electrons only
Answer: (b) Protons + neutrons
Q18. Isotopes have same:
(a) Mass number
(b) Atomic number
(c) Neutrons
(d) Physical properties
Answer: (b) Atomic number
Q19. Isobars have same:
(a) Atomic number
(b) Protons
(c) Mass number
(d) Electrons
Answer: (c) Mass number
Q20. Valency of oxygen (atomic number 8) is:
(a) 1
(b) 2
(c) 6
(d) 8
Answer: (b) 2
Q21. Assertion (A): Most of the space in an atom is empty.
Reason (R): Most alpha particles passed through the gold foil without deflection.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q22. Assertion (A): Neutrons have no charge.
Reason (R): Neutrons are present in the nucleus of atom.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (b) Both A and R are true but R is not correct explanation of A
Q23. Assertion (A): Atomic number determines the identity of an element.
Reason (R): Atomic number is equal to number of protons.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q24. Assertion (A): Isotopes have different chemical properties.
Reason (R): Isotopes have same atomic number.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (d) A is false but R is true
Q25. Assertion (A): Valency of neon is zero.
Reason (R): Neon has completely filled outermost shell.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q26. Assertion (A): Rutherford’s model could not explain stability of atom.
Reason (R): Revolving electrons would lose energy and fall into nucleus.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q27. Assertion (A): Maximum number of electrons in M-shell is 18.
Reason (R): Maximum number of electrons in a shell is given by 2n².
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q28. Assertion (A): Isobars have different atomic numbers.
Reason (R): Isobars belong to different elements.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q29. Assertion (A): Mass of an atom resides mainly in nucleus.
Reason (R): Protons and neutrons are present in nucleus.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q30. Assertion (A): Chlorine has fractional atomic mass 35.5 u.
Reason (R): Chlorine exists in isotopic forms.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: (a) Both A and R are true and R is correct explanation of A
Q31. Which of the following statements are correct about electrons?
i) They are negatively charged
ii) They are present in the nucleus
iii) Their mass is negligible compared to proton
iv) They revolve around the nucleus
a) i, iii and iv
b) i and ii
c) ii and iii
d) i, ii, iii and iv
Answer: a) i, iii and iv
Q32. Which of the following statements are correct according to Thomson’s model of atom?
i) Atom is a positively charged sphere
ii) Electrons are embedded in the positive sphere
iii) Atom has a central nucleus
iv) Atom is electrically neutral
a) i, ii and iv
b) i and iii
c) ii and iii
d) i, ii, iii and iv
Answer: a) i, ii and iv
Q33. According to Rutherford’s experiment, which conclusions were correct?
i) Most of the space in atom is empty
ii) Positive charge occupies very little space
iii) Electrons are present in nucleus
iv) Nearly all mass is concentrated in nucleus
a) i and ii
b) i, ii and iv
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iv
Q34. Which of the following statements are correct about Bohr’s model?
i) Electrons revolve in discrete orbits
ii) Electrons radiate energy while revolving
iii) Only certain orbits are allowed
iv) Electrons do not radiate energy in allowed orbits
a) i and ii
b) i, iii and iv
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, iii and iv
Q35. Which of the following are sub-atomic particles?
i) Proton
ii) Neutron
iii) Electron
iv) Nucleus
a) i and ii
b) i, ii and iii
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iii
Q36. Which of the following statements are correct about isotopes?
i) They have same atomic number
ii) They have different mass numbers
iii) They have different chemical properties
iv) They have same chemical properties
a) i and ii
b) i, ii and iv
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iv
Q37. Which of the following are correct about isobars?
i) Same atomic number
ii) Same mass number
iii) Different atomic numbers
iv) Belong to different elements
a) i and ii
b) ii, iii and iv
c) i and iii
d) i, ii, iii and iv
Answer: b) ii, iii and iv
Q38. Which of the following statements are correct about valency?
i) It depends on outermost shell electrons
ii) Noble gases have zero valency
iii) Oxygen has valency 2
iv) Sodium has valency 2
a) i and ii
b) i, ii and iii
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iii
Q39. Which of the following statements are correct about atomic number and mass number?
i) Atomic number = number of protons
ii) Mass number = protons + neutrons
iii) Atomic number = protons + neutrons
iv) Mass number is denoted by A
a) i and ii
b) i, ii and iv
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iv
Q40. Which of the following statements are correct about electron distribution?
i) Maximum electrons in K-shell is 2
ii) Maximum electrons in L-shell is 8
iii) Maximum electrons in outermost shell is 8
iv) Shells are filled randomly
a) i and ii
b) i, ii and iii
c) ii and iii
d) i, ii, iii and iv
Answer: b) i, ii and iii
Q41. Match the following:
| Column I | Column II |
|---|---|
| (a) Electron | (i) Discovered by Chadwick |
| (b) Proton | (ii) Negatively charged |
| (c) Neutron | (iii) Discovered by Goldstein |
| (d) Canal rays | (iv) No charge |
Answer: a–ii, b–iii, c–iv, d–iii
Q42. Match the following:
| Column I | Column II |
|---|---|
| (a) Atomic number | (i) Protons + Neutrons |
| (b) Mass number | (ii) Protons |
| (c) Valency | (iii) Combining capacity |
| (d) Nucleons | (iv) Protons and Neutrons |
Answer: a–ii, b–i, c–iii, d–iv
Q43. Match the following:
| Column I | Column II |
|---|---|
| (a) K-shell | (i) 8 electrons |
| (b) L-shell | (ii) 2 electrons |
| (c) M-shell | (iii) 18 electrons |
| (d) Outermost shell | (iv) Maximum 8 electrons |
Answer: a–ii, b–i, c–iii, d–iv
Q44. Match the following:
| Column I | Column II |
|---|---|
| (a) Protium | (i) 3₁H |
| (b) Deuterium | (ii) 2₁H |
| (c) Tritium | (iii) 1₁H |
| (d) Hydrogen isotopes | (iv) Same atomic number |
Answer: a–iii, b–ii, c–i, d–iv
Q45. Match the following:
| Column I | Column II |
|---|---|
| (a) Rutherford | (i) Neutron |
| (b) J.J. Thomson | (ii) Nuclear model |
| (c) Chadwick | (iii) Electron |
| (d) Goldstein | (iv) Canal rays |
Answer: a–ii, b–iii, c–i, d–iv
Q46. Match the following:
| Column I | Column II |
|---|---|
| (a) Neon | (i) Valency 2 |
| (b) Oxygen | (ii) Valency 0 |
| (c) Magnesium | (iii) Valency 1 |
| (d) Sodium | (iv) Valency 2 |
Answer: a–ii, b–i, c–iv, d–iii
Q47. Match the following:
| Column I | Column II |
|---|---|
| (a) Isotopes | (i) Same mass number |
| (b) Isobars | (ii) Same atomic number |
| (c) Chlorine-35 | (iii) 17 protons |
| (d) Carbon-14 | (iv) 8 neutrons |
Answer: a–ii, b–i, c–iii, d–iv
Q48. Match the following:
| Column I | Column II |
|---|---|
| (a) Alpha particle | (i) Doubly charged helium ion |
| (b) Gold foil | (ii) Very thin metal sheet |
| (c) 180° deflection | (iii) Small dense nucleus |
| (d) Most particles passed | (iv) Empty space |
Answer: a–i, b–ii, c–iii, d–iv
Q49. Match the following:
| Column I | Column II |
|---|---|
| (a) Atomic number (Z) | (i) Denoted by A |
| (b) Mass number (A) | (ii) Denoted by Z |
| (c) Nitrogen | (iii) 14₇N |
| (d) Carbon | (iv) 6 protons |
Answer: a–ii, b–i, c–iii, d–iv
Q50. Match the following:
| Column I | Column II |
|---|---|
| (a) Complete octet | (i) Highly reactive |
| (b) Incomplete outer shell | (ii) Stable |
| (c) Bohr model | (iii) Discrete orbits |
| (d) Rutherford model | (iv) Electrons revolve around nucleus |
Answer: a–ii, b–i, c–iii, d–iv
SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs – Important Objective Questions
Understanding the Structure of the Atom is a key step in building a strong base in Chemistry. Regular practice of well-designed MCQs based on the latest SEBA (ASSEB) syllabus helps students develop clarity in fundamental concepts and become familiar with the pattern of objective questions asked in exams.
These SEBA Class 9 Science Chapter 4 MCQs cover essential topics such as atomic models, subatomic particles (electrons, protons, and neutrons), electronic configuration, valency, isotopes, and isobars. Since these concepts are directly linked to many higher-level topics, understanding them thoroughly is very important for long-term learning.
Practicing these important objective questions for Class 9 Science helps students improve their conceptual understanding and avoid confusion between similar terms and theories. It also strengthens their ability to answer questions related to atomic structure quickly and accurately in examinations.
Another advantage of consistent MCQ practice is better speed, accuracy, and confidence. Students become more comfortable with different question patterns, manage time efficiently, and can revise the entire chapter effectively before exams.
To perform well in school tests and board-level examinations, students should regularly solve such MCQs and focus on understanding the logic behind each answer. With consistent effort and smart revision, scoring high in this chapter becomes much easier and more achievable.
FAQs – SEBA Class 9 Science Chapter 4 Structure of the Atom MCQs
1. How many MCQs come from Structure of the Atom in SEBA Class 9 exam?
Around 4–6 MCQs usually come from this chapter out of the 45 total MCQs. Focus on atomic models and electrons for easy marks.
2. Which are the most important MCQs for Structure of the Atom Class 9 SEBA?
Questions on Bohr’s model, valency, and isotopes are most repeated. Practice previous papers to understand patterns quickly.
3. Is Structure of the Atom chapter difficult for SEBA Class 9 students?
No, it’s moderate if concepts are clear. Focus on diagrams and definitions—once basics are strong, MCQs become very easy.
4. Where can I download SEBA Class 9 Structure of the Atom MCQs with answers?
You can download chapter-wise MCQs with answers from Assam Eduverse. Always revise solved PDFs before exams for better accuracy.
5. How to prepare Structure of the Atom MCQs quickly before exam?
Revise key formulas, practice 20–30 MCQs daily, and focus on mistakes. Short revision notes help a lot during last-minute study.
6. Are previous year questions enough for Structure of the Atom MCQs SEBA?
Yes, many MCQs repeat with slight changes. Combine previous papers with Assam Eduverse practice sets for full exam preparation.
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