Class 9 • Chemistry • Chapter 4
Structure of the Atom
True & False Quiz
Proton. Neutron. Electron.
✓True
✗False
25
Questions
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Ch.4
Chapter
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IX
Class
Why True & False for Structure of the Atom?
How this format sharpens your conceptual clarity
🔵 Structure of the Atom explains why elements behave the way they do — valence electrons, shells, and atomic models are the basis of the periodic table and bonding.
✅ T/F tests Thomson's, Rutherford's, and Bohr's models; atomic number vs mass number; isotopes vs isobars; and electron configuration.
🎯 Atomic number (Z) = number of protons = number of electrons in a neutral atom; Mass number (A) = protons + neutrons — NOT protons alone.
📋
Read each statement carefully. Click True or False — instant feedback with explanation appears. Submit anytime; unattempted questions are marked Skipped.
Q 1
An atom is electrically neutral because the number of protons equals the number of electrons.
Q 2
J.J. Thomson discovered the neutron.
Q 3
The nucleus of an atom contains protons and neutrons.
Q 4
Electrons are found in the nucleus of an atom.
Q 5
Rutherford's alpha particle experiment led to the discovery that most of the atom’s space is empty.
Q 6
Bohr’s atomic model says electrons revolve in fixed energy levels or orbits.
Q 7
The charge of a proton is equal in magnitude but opposite to the charge of an electron.
Q 8
Isotopes have the same number of protons but different number of neutrons.
Q 9
The mass number of an atom is the sum of its protons and electrons.
Q 10
Only hydrogen atoms have no neutrons.
Q 11
The value of atomic number (Z) can be same for two different elements.
Q 12
All canal rays are composed of neutrons.
Q 13
The electron was discovered by J.J. Thomson using cathode ray experiment.
Q 14
Electrons are negatively charged particles.
Q 15
In the modern atomic model, protons and neutrons are confined to the nucleus.
Q 16
The sum of protons and neutrons is called the atomic number.
Q 17
Lewis symbols represent atoms using their valence electrons.
Q 18
Valency refers to the combining capacity of an atom.
Q 19
Dalton believed atoms are indivisible.
Q 20
The first atomic model was given by Rutherford.
Q 21
An element with atomic number 8 has 8 protons and 8 electrons.
Q 22
The number of neutrons in atom can be found by subtracting atomic number from mass number.
Q 23
Isobars have the same atomic number but different mass numbers.
Q 24
Shells in an atom are represented as K, L, M, N.
Q 25
The central core of an atom is called nucleus.
Key Takeaways — Structure of the Atom
Core facts for CBSE Boards & exams
1
Thomson's model: atom is a uniform positive sphere with electrons embedded (plum-pudding).
2
Rutherford's model: dense positive nucleus with electrons orbiting; BUT could not explain stability.
3
Bohr's model: electrons orbit in fixed energy shells; energy absorbed = shell jump outward; emitted = inward.
4
Electron configuration rule: shell capacity = 2n² (K=2, L=8, M=18); valence shell fills last.
5
Isotopes: same atomic number (Z), different mass number (A) — e.g. ¹H, ²H (deuterium), ³H (tritium).
6
Isobars: same mass number (A), different atomic number (Z) — e.g. ⁴⁰Ca and ⁴⁰Ar.