Number of protons in ⁸⁰₃₅Br:
- 25
- 35
- 45
- 80
Show answer and explanation
Answer: B. 35
The atomic number (subscript, 35) gives the number of protons directly.
Matric Chemistry: Structure of Atoms, questions with answers
Practise 18 real Federal Board questions on Structure of Atoms from 2023 to 2026. See the answer and explanation as soon as you answer.
18real questions
5multiple choice
5exam sessions
About Structure of Atoms in Matric Chemistry
Structure of Atoms is one of the 11 main chapters in our Federal Board Matric Chemistry question bank (9th class), and about 5% of its real questions come from it. Tayyari Karo has 18 real questions on this chapter from 2023 to 2026; 5 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 10 easy, 8 medium.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
Electrons in higher energy levels are ________ (from nucleus).
- Closer to nucleus
- Less energetic
- Stable
- Far from nucleus
Show answer and explanation
Answer: D. Far from nucleus
Higher energy levels (larger n) correspond to electron shells that are farther from the nucleus.
Which statement about isotope of chlorine ³⁵₁₇Cl is NOT correct?
- It has 17 electrons
- It has 17 protons
- It has 17 neutrons
- Its mass number is 35
Show answer and explanation
Answer: C. It has 17 neutrons
Neutrons = mass number − protons = 35 − 17 = 18, not 17, so 'it has 17 neutrons' is the incorrect statement.
The atomic mass number of an element is 35. It has 17 protons in its nucleus. What number of neutrons it will have in its nucleus?
- 17
- 18
- 19
- 20
Show answer and explanation
Answer: B. 18
Number of neutrons = mass number − number of protons = 35 − 17 = 18.
Which one of the following is used to estimate the age of carbon-containing substances in a process called carbon dating?
- C-12
- C-13
- C-14
- C-15
Show answer and explanation
Answer: C. C-14
The radioactive isotope carbon-14 decays at a known rate and is used in carbon dating.
An element exists as two isotopes: ⁶⁴X (abundance 30%), ⁶⁶X (abundance 70%). Calculate the average relative atomic mass of element X.
Show model answer
Average atomic mass = Σ(isotope mass × fractional abundance)
= (64 × 0.30) + (66 × 0.70)
= 19.2 + 46.2
= 65.4 amu
Write relative charge and relative mass of an electron, proton, and neutron.
Show model answer
Electron: relative charge = −1, relative mass ≈ 1/1836 (negligible, ≈0).
Proton: relative charge = +1, relative mass = 1.
Neutron: relative charge = 0, relative mass = 1.
Describe Rutherford's experiment with its conclusions and defects.
Show model answer
Rutherford's α-scattering experiment: A narrow beam of fast-moving, positively charged alpha (α) particles from a radioactive source was directed at a very thin gold foil, surrounded by a circular fluorescent (ZnS) screen to detect where the particles landed.
Observations: Most α-particles passed straight through undeflected; a few were deflected at small angles; a very small fraction bounced almost straight back.
Conclusions: (1) Most of the atom is empty space (since most particles passed through). (2) The atom has a tiny, dense, positively charged nucleus at its centre (causing the large deflections/rebounds of the positively charged α-particles). …
The full model answer is in the app.
Sessions with Structure of Atoms questions
| Session | Questions |
|---|---|
| 2026 Annual | 2 |
| 2025 1st Annual | 3 |
| 2025 2nd Annual | 3 |
| 2024 Annual | 4 |
| 2023 Annual | 6 |
Common questions
What does the Structure of Atoms chapter cover on this page?
18 real Federal Board (FBISE) Chemistry questions on Structure of Atoms from 2023 to 2026, for 9th class. Each one shows the session it came from.
Are the answers official?
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
Is it free?
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks the full question bank.